Today I switched back to my Atheros card and I transferred _without_ error in scp more times an iso image without any error. I'm using the kernel 2.6.32-020632-generic from the Ubuntu repository.
Here's some tech details. I'm really positively surprised and I'm still using this wifi card in order to check any further issue.

09:00.0 Network controller: Atheros Communications Inc. AR928X Wireless Network Adapter (PCI-Express) (rev 01)
	Subsystem: Foxconn International, Inc. Device e01f
	Flags: bus master, fast devsel, latency 0, IRQ 19
	Memory at f0000000 (64-bit, non-prefetchable) [size=64K]
	Capabilities: <access denied>
	Kernel driver in use: ath9k
	Kernel modules: ath9k

root@angelo-laptop:~# scp -rv "angelo@server:~/incoming/iso.iso" .
Executing: program /usr/bin/ssh host server, user angelo, command scp -v -r -f ~/incoming/iso.iso
OpenSSH_5.1p1 Debian-6ubuntu2, OpenSSL 0.9.8g 19 Oct 2007
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to server [xxx.xxx.xxx.xxx] port 22.
debug1: Connection established.
debug1: permanently_set_uid: 0/0
debug1: identity file /root/.ssh/identity type -1
debug1: identity file /root/.ssh/id_rsa type -1
debug1: identity file /root/.ssh/id_dsa type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.1p1 Debian-6ubuntu2
debug1: match: OpenSSH_5.1p1 Debian-6ubuntu2 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.1p1 Debian-6ubuntu2
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-cbc hmac-md5 none
debug1: kex: client->server aes128-cbc hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'server' is known and matches the RSA host key.
debug1: Found key in /root/.ssh/known_hosts:1
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Trying private key: /root/.ssh/identity
debug1: Trying private key: /root/.ssh/id_rsa
debug1: Trying private key: /root/.ssh/id_dsa
debug1: Next authentication method: password
angelo@server's password: 
debug1: Authentication succeeded (password).
debug1: channel 0: new [client-session]
debug1: Requesting <email address hidden>
debug1: Entering interactive session.
debug1: Sending environment.
debug1: Sending env LANG = it_IT.UTF-8
debug1: Sending command: scp -v -r -f ~/incoming/iso.iso
Sending file modes: C0664 719807740 Up - Pixar Disney 2009 iTA spledido.avi
Sink: C0664 719807740 iso.iso
iso.iso                                                                                                                                 100%  686MB   2.0MB/s   05:36    
debug1: client_input_channel_req: channel 0 rtype exit-status reply 0
debug1: client_input_channel_req: channel 0 rtype <email address hidden> reply 0
debug1: channel 0: free: client-session, nchannels 1
debug1: fd 0 clearing O_NONBLOCK
debug1: fd 1 clearing O_NONBLOCK
Transferred: sent 177952, received 720513304 bytes, in 343.5 seconds
Bytes per second: sent 518.1, received 2097668.4
debug1: Exit status 0


Cheers
Angelo