There's nothing wrong with the 955 in gaming, I have it and I love it.
I mean yes, the i5/i7's can OC better and beat the 955 in performance, but my god it's not like that means it's slow. It's not like the 955 is gonna bottleneck you.
It's just a matter of choice.
And the unlocked multiplier makes it so easy to overclock.
I'm at 3.7 GHz on the stock HS/F.. Takes like 2 minutes in the BIOS.. I am quite enjoying mine.
So you could go with an i5, but in all honesty I don't think it REALLY makes a difference as far as gaming is concerned. At least my opinion.
The VC will bottleneck you long before the processor does.