DirectX 10 is Windows Vista only, which will be out early next year. DirectX 10 cards will appear late this year at the earliest.
Assuming that you like the games on the 360 about as much as the games on the PC, I say get a 360 now and save your pennies for a DirectX 10 capable card early next year. A card bought today at your price point will struggle with UT 2007 at moderately high settings.
Those cards should be OK with those settings. UT 2007 is scheduled for release in Q1 or the first half of 2007. I still say wait for the PC upgrade and get a 360 if there are games for the 360 that interest you.
Thanks for the input guys, the reason I brought this question up can be summed up in another thread I started, I really just wanna play ncaa Football 2007, and I've never been a big sony fan. Well off to gamestop to check on a used 360...
the arrogance of officialdom should be tempered and controlled... People must again learn to work, instead of living on public assistance. Cicero , 55 BC