The big challenge is to make a game that was designed solely for the console... to take advantage of every last little corner of that console, to fill every little crack and run as many threads as we could and do as much to exploit the power of that machine, and make it run well on enough PCs to be worth releasing. That's a challenge.
UT will help us there, because Unreal Tournament 3 will be kind of our vanguard PC product, and it's helping us get optimisation on the PC. So it's just a matter of, now, can we make Gears run on enough PCs that it's worth selling...or do we have to wait in five years until everyone has a PC that can run it?