Yes, you need an NVIDIA 8000 series.
Do not, I repeat, DO NOT get one that is less than 512mb if you want to run all the features without major problems.
Your best bet right now is the 8800gt.
The GT is the lowest priced 8800, and the 8800 is the best of the 8000 series.
The 8800gt costs around $229 at Tiger Direct, but you might find one on sale cheaper somewhere else.
Dude, the topic of cards for X10 has been covered and there is even a sticky about it.
So, read the stickies (new members should read them all before posting), and use that "Thread Subject Search" box at the bottom of this page.
Not only does it have most of the answers that you need, but it will prevent people from torching you for posting questions that have already been answered.
Welcome and good luck.