I see a lot a requests for help building a PC in the $1000 range.
For $1000 you can not buy the Ultimate machine on Earth, but it will be pretty nice.
If you have more budget, get better parts, but please don't get less.
I feel this is a minimum starting point for a high performance PC that can be upgraded for years to come.
Use this only as a guide. Your mileage may vary.
Quite frankly, if you're gonna spend $1000, you'd get a much better build for $1050 if you buy a Radeon 6950 and unlock it to a 6970 (6950 is barely better than GTX 560 Ti not unlocked) or if you just buy a GTX 570 for $1100 total. A 5870's better too.
Why_Me, why the choice of GTX 560 Ti (Ti's kind of a waste of time to type)?