If you don't want to do gaming
You can get an excellent PC for only $1k.
For MultiMedia Editing you can go with any lower mid-range card.
Like Radeon 5750.
For a little more you can get GeForce GTS 250. Which is good in gaming performance but then again i assume you don't have any plans for that.
Good luck and consider me opinion
You can save alot of money
what about the: ATI® Radeon™ HD 5970 2GB GDDR5 DX11..?? isn't this the best GPU at the moment..??
Whats the deal with the NVIDIA® Quadro™ FX Series..?? why the eff are they so dang expensive..??
Whats the difference between these cards, I notice the ATI is for like gaming and the Quadro's are for like workstations or something..??
Im a noob when it comes to GPU cards.. please help me make sense of it all guys..??
The 5970 is indeed the best single card, but unless your editing applications can utilize GPU power (pretty much all of them can't), it's money wasted.
The Quadro series are professional graphics cards for workstations - things like Solidworks, CAD, 3D modeling applications, Matlab, etc. That's why they're expensive. They make poor companions for gaming or media-based PCs.
Nvidia also has a consumer series just like ATI does (ATI also has a workstation series). You should, as mfarrukh said, be looking for a lower-midrange card. The only work your card will be doing is accelerating playback, really, which isn't very tough to do. A 5750 or an nvidia 250 will be more than enough for you. As he/she also mentioned, you don't need $3000 for a good editing PC...$1000 will be more than enough.