Mostly agree with Jesse. I'd consider getting the 3700+ and save $100 or more (it was $211 recently at zipzoomfly.com). I'd personally stay away from SLi, too. I'd take a look at the Abit AN8 Ultra or Epox 9NPA+ Ultra, too - great mobos at a reasonable price. The AN8 has a great OC utility for beginners - uGuru. The 6800GS is on the same performance level as the 6800GT, but costs significantly less.
What's your budget and what will be the other usage for the system?