Comment 5 for bug 337311

Teej: "MadWiFi and ndis drivers perform better on noisy environments than ath5k because we don't support Adaptive Noise Immunity (ANI) yet." (& tx-power calibration) - possibly this is the cause of your problem, since re-orienting or moving the laptop will affect the noise and requiring tx power.

Slobodan: Installing the latest from compat-wireless http://linuxwireless.org/download/compat-wireless-2.6/ may provide some performance improvement - for me it stopped the stuttering connection you describe.