I found one of the benchmarks.
On this one the 750 beats the 661 bu +30%! PassMark Intel vs AMD CPU Benchmarks - High End
But that's just a single one. Need to find some for gaming, not sure what passmark does exactly but simple number crunching might benefit from cache, whereas gaming not so much.
Aaaah, the 750 is a quad core and the 661 is a dual core, that's why.
I think maybe I'd go for the 750... my quad core laptop kills my dual core desktop in photoshop.