The HD2600 is you best choice of what you've listed, it will destroy any GF7600, and will compete with the GF7900 depending on game (a little low in older games but noticeably fast in new shader heavy games).
For crysis, nothing less than a GF8600 or HD2600 will do, the GF7600/X1650/GF7900 will all be totally dominated in that shader heavy game.
Don't know if you've already bought your card or not, but ignore all the older options and go with at least a HD2600/GF8600, and even then I'd say if you can get your hands on the HD3850 you'd be much better off now and in the long term.