Here is my top 5 choices for video cards, they are not cheap
1. ATI Radeon HD 5870
ATI's Radeon 5800 chipsets represent one of the largest leaps in video card performance in a long time. The HD 5870 has quite easily taken the top spot for single-GPU performance, and also holds its own against many of the dual-GPU cards on the market. The HD 5870 has 1 GB of GDDR5 onboard and a core clock speed of 850MHz, as well as full support for DirectX 11. It is a little big and occupies two slots in your system. While there are less costly cards available that will probably get the job done, we've rarely seen a high-end offering like this launch at such an attractive price point.
2. ATI Radeon HD 5850
The second card released in Radeon's 5800 series is the HD 5850. Although a little slower than the HD 5870, it has most of the same features, including DX11, Eyefinity, HDMI bitstreaming, supersample anti-aliasing, and 1 GB of GDDR5 memory. As well as being less expensive than the HD 5870, 5850s require less power and tend to be shorter in length. Comparable to a GTX 285 in speed, these cards are a great deal right now, but retailers have been selling out of them very quickly.
3. ATI Radeon HD 5970
Radeon's dual-GPU monster is the HD 5970, which arrived in late 2009 and took its place as the fastest discrete video card on the market. Essentially, it is the equivalent of running two HD 5870s in CrossFire, although the chips and memory aren't clocked quite as fast, primarily to keep power consumption in check. As it is the card can draw close to 300W, and has both a 6-pin and an 8-pin auxiliary connector. The HD 5970 uses a single PCB, and the result is a very long card that will only fit into the roomiest cases. There's ample processing here even for the largest monitors, but it's well beyond the average budget..
4. Nvidia GeForce GTX 295
Not to be outdone by ATI's dual GPU Radeon HD 4870 X2, Nvidia released another dual GPU card in January 2009. The GTX 295 is made up of 2 GTX 260 GPUs running in SLI on a single card, except that these chips have 240 stream processors each rather than 216, and they're made with a smaller 55 nm process. Nvidia has used the 2 PCB approach instead of trying to put 2 GPUs on one board the way ATI does. While the GTX 295 offers impressive performance for a single card, they don't come cheap.
5. ATI Radeon HD 4870 X2
Another one of ATI's dual GPU cards, this time with two HD 4870 graphics processors and a whopping 2 GB of memory onboard. It's a close race between the HD 4870 X2, the GeForce 9800 GX2, and the GeForce GTX 280 in terms of overall performance, with each showing strengths in certain games. This card definitely puts out some impressive framerates. Of course, like other dual GPU cards, they tend to consume a lot of power and produce a lot of heat, but their price has dropped dramatically in recent months.
Cheaper cards can be found through google