I am a linux user and read that ati cards work great with the open source neaveau drivers is that right? Is it also the case for gaming too?

Of course I am not playing top of the line games on this old machine but I like isometric rpgs or stategies which it can still handle comfortably for the most part except big action scenes.

I guess an older ati card would not cost much now?

What line from what to what would work with my mobo? I would want at least equivalent to 660gtx but might as well know what the best that was made too and maybe even get a modest upgrade.