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Well, since the GTX 650 Ti Boost is an entry level card, I expect that for the most part your system will not be held back too much by your other components. You really don't have much choice, since I wouldn't recommend anything lower than a GTX 650 Ti Boost for any system, anyway.
the 650ti is not entry level, and is a really decent card.
http://www.tomshardware.com/reviews/gaming-graphics-card-review,3107-3.html
it's toms own sub 200 recommendation, so I wouldn't be so dismissive. It will give high settings in Battlefield 3 at 1080p so as I said, entry level it's most certainly not. With the OP's system, this would be a good balanced match, and give some life to his system, which is still decent for med-high gaming.
to the OP, your CPU is fine for the GPU and will not bottleneck, if that's what your referring too!
enjoy
edit: just saw your second post......with a 660/ti you may be pushing it without overclocking the cpu. Saying that, it won't be a missive hit, with those cards your talking a few fps extra per 100mhz overclock. Not much difference between 60 fps and 65-70 IMO.