There are many wireless drivers available for Linux: ath5k, madwifi, ndiswrapper…etc. For the model described in the title (Atheros), madwifi latest version exists in Ubuntu 8.10 by default, and I faced the following problems:

1. Very weak signal, even if I’m very close to the access point!
2. Cannot connect to ad-hoc networks (via Internet Connection Sharing from my home PC)
3. Frequent disconnections

I have tried both ath5k and ndiswrapper; ndiswrapper ROCKS! I removed all my wireless drivers and installed the ndiswrapper module, attached my .inf file to it and worked GREAT! You must try it out if you face the same or similar problems