The i5 650 is still a pretty fast dual core, it performs close to the Sandy Bridge i3s. In single threaded workloads you may actually equal a Sandy i3 thanks to Turbo Boost, which the i3 doesn't have. You should be okay with that CPU for most titles, though your CPU may hold you back in games that really like quad core CPUs, eg. Battlefield 3 on 64 player maps, GTA IV.
I wouldn't worry about bottle neck. Tom's ranks the i5-650 equal to the better Phenom II x4s: http://www.tomshardware.com/reviews/gaming-cpu-review-o...
Gaming is mainly about the card anyway. Just ask yourself... how slow of a card would I put up with so as to not have any bottle neck? I know my answer. I'd go for it.