i5 2500 is awesome...but the 460 is a bit outdated...the 4100 is better at overclocking but has less performance....the gtx 550ti is much more current for the gpu...the i3 2150 is underpowered for gaming purposes...but if I had to choose between one or the other...the 2500 wins hands down...although beware...since it's not a K version intel cpu..there's very little overclocking as in 1-2%...that's it...the fx4100 is more overclockable but has less performance.
so I would go with the 2500 and save money for a better gpu later...and then sell the 460 to help defray costs of a better gpu.
It is true that the 2500 generally outperforms the 4100, but with stock cooling the 4100 can hit 4.4GHz and stay nice and cool. That would allow it to match the performance of the 2500, So overall I would say your best bet is the FX-4100 kit, because you'll have the better video card and ram. (Note: I have and FX-4100, and I run a stable 4.6GHZ with stock cooling on all four cores) If the Intel build were a 2500k, I'd say hop on it