Right now is a great time to not get screwed by getting a new computer for gaming, by not buying one.
Thats right for a limited time you can not fuck your self over by wasting money when both Nvidia and Ati are about to release their next gen specs(thus driving down prices)!
But wait their is more! If you want your system to have an extended lifetime and be able to upgrade you will want to bite the bullet on DDR3. Thats right, its sad but to be worth it your going to want ddr3 support or else your going to need a new motherboard down the road. Why sad, well DDR3 chips are still crazy expensive and will not be "affordable" for another 9-12 months...
Technologically the best time to buy is sometime this fall after Nvidia releases the GT200 core.