If the system you have is working well now with the games that you play, then hold on for a bit. If not, get system now (and don't spend a ton on the Gfx card) but when building it plan for getting a new Gfx card next year. Oh, and make sure that the power supply you purchase will be adequate for the "next year" solution.

Owain and Paveway actually "NEEDED" a new system (hell they needed one last year)! But the systems that I put together for them specifically were tuned for them buying a new Gfx card next year when the Dx10 stuff comes down a bit.

Taxman

"Any group is weaker than a man alone unless they are perfectly trained to work together."
- Robert A. Heinlein, Starship Troopers