You can see get a lot of great graphic features out of the game in dx8.1 mode, I was running a fx5900nu for a while, having a dx9 card just gives all the purty reflections ( trust me, "reflect all" will not give you those )
RAM is definately a big factor on how far you can overclock your processor with amd64.
I really want to overclock my processor right now, but I have generic DDR400... I get max temps of 34C load from my processor.
.. In addition... Most TV Tuner cards will have video input. Any video card with "VIVO" (Video In, Video Out) Can be used to capture stuff off an outside device via s-video/composite. For audio capture side, you can get a connector that takes red,white composite to stereo headphone jack...
The video's probably require a specific codec that you don't have.
http://www.headbands.com/gspot/download.html - GSpot - A good program for seeing what codec is need, you open a video file with this program, and it will tell you what video and audio codecs are required, so if the codec pack...
I've seen this a lot before with any with an ATi card and High AA/AF settings, So just mix and match AA/AF settings till you get to a point where things work out.
Anyone can use the CVS and compile Cedega themselves, so you can get it for free, it's just a biznatch to do! But I am sure there are guides if you just concentrate for a second that you can use. And if you are already on linux you probably at least have some skill to get that done.
Go for MSI! They are a great manufacture of all their products in general!
I thought 6800ultra did better in HL2 than any ati card... .. oh well 6800ultra does perform very well for all other games too along with having Shader Model 3 ( dx9c )
All and all, If you can manage to setup your linux install perfectly ( with graphics drivers and all ) you can actually play a lot of games, even non-linux games through Cedega ( gaming version of wine, use to be winex ) Some games even get better fps in linux. As for knowledge of what games...