I tried using the up to date compatwireless drivers and still find myself unable to connect to unencrypted B access points at my school. Although the problem is only with some of the access points. Below is an output of the relevant portion of dmesg.
[   51.120088] iwl3945: Intel(R) PRO/Wireless 3945ABG/BG Network Connection driver for Linux, 1.2.26k
[   51.120093] iwl3945: Copyright(c) 2003-2008 Intel Corporation
[   51.120189] ACPI: PCI Interrupt 0000:02:00.0[A] -> GSI 16 (level, low) -> IRQ 16
[   51.120211] PCI: Setting latency timer of device 0000:02:00.0 to 64
[   51.120233] iwl3945: Detected Intel Wireless WiFi Link 3945ABG
[   51.162781] iwl3945: Tunable channels: 11 802.11bg, 13 802.11a channels
[   51.164328] phy0: Selected rate control algorithm 'iwl-3945-rs'
[   51.181679] ACPI: PCI Interrupt 0000:02:00.0[A] -> GSI 16 (level, low) -> IRQ 16
[   51.281520] Intel(R) PRO/1000 Network Driver - version 7.3.20-k2-NAPI
[   51.281524] Copyright (c) 1999-2006 Intel Corporation.
[   51.281669] PCI: Enabling device 0000:05:00.0 (0000 -> 0003)
[   51.281676] ACPI: PCI Interrupt 0000:05:00.0[A] -> GSI 18 (level, low) -> IRQ 18
[   51.281693] PCI: Setting latency timer of device 0000:05:00.0 to 64
[   51.339740] e1000: 0000:05:00.0: e1000_probe: (PCI Express:2.5Gb/s:Width x1) 00:16:36:9d:e8:04
[   51.405426] ADDRCONF(NETDEV_UP): wlan0: link is not ready
[   51.405988] e1000: eth0: e1000_probe: Intel(R) PRO/1000 Network Connection
[   53.880810] ADDRCONF(NETDEV_UP): eth0: link is not ready
[   67.950659] wlan0: Initial auth_alg=0
[   67.950663] wlan0: authenticate with AP 00:a0:f8:a3:7f:57
[   67.953868] wlan0: RX authentication from 00:a0:f8:a3:7f:57 (alg=0 transaction=2 status=0)
[   67.953871] wlan0: authenticated
[   67.953873] wlan0: associate with AP 00:a0:f8:a3:7f:57
[   68.150533] wlan0: associate with AP 00:a0:f8:a3:7f:57
[   68.350280] wlan0: associate with AP 00:a0:f8:a3:7f:57
[   68.549990] wlan0: association with AP 00:a0:f8:a3:7f:57 timed out
[   71.097998] wlan0: Initial auth_alg=0
[   71.098004] wlan0: authenticate with AP 00:a0:f8:a3:7f:57
[   71.098796] wlan0: Initial auth_alg=0
[   71.098799] wlan0: authenticate with AP 00:a0:f8:a3:7f:57
[   71.098913] wlan0: RX authentication from 00:a0:f8:a3:7f:57 (alg=0 transaction=2 status=0)
[   71.098916] wlan0: authenticated
[   71.098918] wlan0: associate with AP 00:a0:f8:a3:7f:57
[   71.099145] wlan0: authentication frame received from 00:a0:f8:a3:7f:57, but not in authenticate state - ignored
[   71.128833] wlan0: associate with AP 00:a0:f8:a3:7f:57
[   71.148531] wlan0: associate with AP 00:a0:f8:a3:7f:57
[   71.173210] wlan0: association with AP 00:a0:f8:a3:7f:57 timed out
[   72.571202] wlan0: Initial auth_alg=0
[   72.571207] wlan0: authenticate with AP 00:a0:f8:a3:7f:57
[   72.572853] wlan0: Initial auth_alg=0
[   72.572855] wlan0: authenticate with AP 00:a0:f8:a3:80:79
[   72.573402] wlan0: Initial auth_alg=0
[   72.573404] wlan0: authenticate with AP 00:a0:f8:a3:80:79
[   72.574528] wlan0: RX authentication from 00:a0:f8:a3:80:79 (alg=0 transaction=2 status=0)
[   72.574531] wlan0: authenticated
[   72.574534] wlan0: associate with AP 00:a0:f8:a3:80:79
[   72.575414] wlan0: authentication frame received from 00:a0:f8:a3:80:79, but not in authenticate state - ignored
[   72.585521] wlan0: associate with AP 00:a0:f8:a3:80:79
[   72.603400] wlan0: associate with AP 00:a0:f8:a3:80:79
[   72.618334] wlan0: association with AP 00:a0:f8:a3:80:79 timed out
[   74.272215] wlan0: Initial auth_alg=0
[   74.272219] wlan0: authenticate with AP 00:a0:f8:a3:81:b1
[   74.272812] wlan0: Initial auth_alg=0
[   74.272814] wlan0: authenticate with AP 00:a0:f8:a3:81:b1
[   74.298279] wlan0: authenticate with AP 00:a0:f8:a3:81:b1
[   74.314653] wlan0: authenticate with AP 00:a0:f8:a3:81:b1
[   74.328658] wlan0: authentication with AP 00:a0:f8:a3:81:b1 timed out
[   80.424585] wlan0: Initial auth_alg=0
[   80.424589] wlan0: authenticate with AP 00:a0:f8:a3:81:b1
[   80.425645] wlan0: Initial auth_alg=0
[   80.425648] wlan0: authenticate with AP 00:a0:f8:a3:81:b1
[   80.622529] wlan0: authenticate with AP 00:a0:f8:a3:81:b1
[   80.822259] wlan0: authenticate with AP 00:a0:f8:a3:81:b1
[   81.021108] wlan0: authentication with AP 00:a0:f8:a3:81:b1 timed out
[   89.332948] wlan0: Initial auth_alg=0
[   89.332953] wlan0: authenticate with AP 00:a0:f8:a3:81:b1
[   89.334454] wlan0: Initial auth_alg=0
[   89.334457] wlan0: authenticate with AP 00:a0:f8:a3:80:79
[   89.335192] wlan0: Initial auth_alg=0
[   89.335197] wlan0: authenticate with AP 00:a0:f8:a3:80:79
[   89.335216] wlan0: RX authentication from 00:a0:f8:a3:80:79 (alg=0 transaction=2 status=0)
[   89.335220] wlan0: authenticated
[   89.335224] wlan0: associate with AP 00:a0:f8:a3:80:79
[   89.335538] wlan0: authentication frame received from 00:a0:f8:a3:80:79, but not in authenticate state - ignored
[   89.349904] wlan0: associate with AP 00:a0:f8:a3:80:79
[   89.367728] wlan0: associate with AP 00:a0:f8:a3:80:79
[   89.381038] wlan0: association with AP 00:a0:f8:a3:80:79 timed out
[   90.690420] wlan0: Initial auth_alg=0
[   90.690425] wlan0: authenticate with AP 00:a0:f8:a3:80:79
[   90.691912] wlan0: Initial auth_alg=0
[   90.691914] wlan0: authenticate with AP 00:a0:f8:ab:27:7b
[   90.692446] wlan0: Initial auth_alg=0
[   90.692449] wlan0: authenticate with AP 00:a0:f8:ab:27:7b
[   90.692456] wlan0: RX authentication from 00:a0:f8:ab:27:7b (alg=0 transaction=2 status=0)
[   90.692458] wlan0: authenticated
[   90.692460] wlan0: associate with AP 00:a0:f8:ab:27:7b
[   90.692891] wlan0: authentication frame received from 00:a0:f8:ab:27:7b, but not in authenticate state - ignored
[   90.737127] wlan0: associate with AP 00:a0:f8:ab:27:7b
[   90.764970] wlan0: associate with AP 00:a0:f8:ab:27:7b
[   90.777884] wlan0: association with AP 00:a0:f8:ab:27:7b timed out
[   93.950836] wlan0: Initial auth_alg=0
[   93.950843] wlan0: authenticate with AP 00:a0:f8:ab:27:7b
[   93.951400] wlan0: Initial auth_alg=0
[   93.951402] wlan0: authenticate with AP 00:a0:f8:ab:27:7b
[   93.951982] wlan0: RX authentication from 00:a0:f8:ab:27:7b (alg=0 transaction=2 status=0)
[   93.951984] wlan0: authenticated
[   93.951986] wlan0: associate with AP 00:a0:f8:ab:27:7b
[   93.952281] wlan0: authentication frame received from 00:a0:f8:ab:27:7b, but not in authenticate state - ignored
[   93.972082] wlan0: associate with AP 00:a0:f8:ab:27:7b
[   94.008133] wlan0: associate with AP 00:a0:f8:ab:27:7b
[   94.046653] wlan0: association with AP 00:a0:f8:ab:27:7b timed out
[   98.387378] wlan0: Initial auth_alg=0
[   98.387382] wlan0: authenticate with AP 00:a0:f8:a3:81:7a
[   98.388458] wlan0: Initial auth_alg=0
[   98.388460] wlan0: authenticate with AP 00:a0:f8:a3:81:7a
[   98.388469] wlan0: RX authentication from 00:a0:f8:a3:81:7a (alg=0 transaction=2 status=0)
[   98.388472] wlan0: authenticated
[   98.388474] wlan0: associate with AP 00:a0:f8:a3:81:7a
[   98.388798] wlan0: authentication frame received from 00:a0:f8:a3:81:7a, but not in authenticate state - ignored
[   98.388941] wlan0: authentication frame received from 00:a0:f8:a3:81:7a, but not in authenticate state - ignored
[   98.460297] wlan0: associate with AP 00:a0:f8:a3:81:7a
[   98.505109] wlan0: associate with AP 00:a0:f8:a3:81:7a
[   98.556797] wlan0: association with AP 00:a0:f8:a3:81:7a timed out
[  101.834872] wlan0: Initial auth_alg=0
[  101.834876] wlan0: authenticate with AP 00:a0:f8:a3:81:7a
[  101.835194] wlan0: RX authentication from 00:a0:f8:a3:81:7a (alg=0 transaction=2 status=0)
[  101.835197] wlan0: authenticated
[  101.835200] wlan0: associate with AP 00:a0:f8:a3:81:7a
[  101.868506] wlan0: associate with AP 00:a0:f8:a3:81:7a
[  101.939018] wlan0: associate with AP 00:a0:f8:a3:81:7a
[  101.961054] wlan0: association with AP 00:a0:f8:a3:81:7a timed out
[  103.127436] wlan0: Initial auth_alg=0
[  103.127441] wlan0: authenticate with AP 00:a0:f8:ab:29:33
[  103.128656] wlan0: Initial auth_alg=0
[  103.128659] wlan0: authenticate with AP 00:a0:f8:ab:29:33
[  103.128667] wlan0: RX authentication from 00:a0:f8:ab:29:33 (alg=0 transaction=2 status=0)
[  103.128669] wlan0: authenticated
[  103.128671] wlan0: associate with AP 00:a0:f8:ab:29:33
[  103.128678] wlan0: authentication frame received from 00:a0:f8:ab:29:33, but not in authenticate state - ignored
[  103.129885] wlan0: authentication frame received from 00:a0:f8:ab:29:33, but not in authenticate state - ignored
[  103.140226] wlan0: associate with AP 00:a0:f8:ab:29:33
[  103.153319] wlan0: associate with AP 00:a0:f8:ab:29:33
[  103.169607] wlan0: association with AP 00:a0:f8:ab:29:33 timed out