The linux client is going to be released very soon. But remember that everyones "very soon" means a different timeframe. I like ET: QW more the more I play it (when being on a server without beginners that make you cry ). My favourite Campaign is Africa especially with Slipgate and Island, but I haven't played some maps for really long yet.
Will a 7600GT OC be able to handle 1280x1024 with decent settings?
It also depends on your CPU, but it could be able to handle middle settings w/o AA. Try the demo client on Windows or the Linux demo once it's out (I guess that there will be one [if yes - very soon]).
You know, I played the multiplayer beta on Windows, and it was a huge disappointment for me. Graphics are horrible (and yes, I cranked everything to max), gameplay sucks and quite frankly, I think id Software lost the edge. Far Cry, a 3 year-old game, looks and acts (as in the bot AI) *much* better than anything id Software released in the last 7 years. With their current plans to introduce Rage, I'm seeing another Doom 3 in the making: 2-3 years late and already surpassed by better games (like the upcoming Far Cry 2, which appears to be similar in nature). Sad, really, as I still want to support id for all the games they've made available on GNU/Linux.
Now I'm just praying to G-d Unreal Tournament 3 will be everything I hoped for...