You'll get different answers on this from different people. Like GR1M_ZA said, if money isn't an issue, then why not get the i7?
I'm building a new system for myself next week, and I'm going with the i5. Some people say to get the i7 so you're more 'futureproof'. I can't argue with that, as the hyperthreading on the i7 may be more useful in the future. For TODAY's games however, you won't see much performance difference between the two CPUs. I typically upgrade my system every two years, so I don't think the i7 will do me any good.
So, the answer to your question? It's really your call. Can't go wrong with either of those two.
Edited. Brain fart. Thanks mrmez