If you have the option of buying online, get this for $10 more:
EVGA 512MB 8800GT
^ This thing absolutely slaughters the 8600GT in everything. Expect decent framerates in Crysis on high (at resolutions below 1680x1050). At Best Buy, this'd probably be at least $70 more than it is online.
If you have to buy in store, I don't think you have much choice. The 8600GT is all you can get for $150 at Circuit and Best Buy. Pretty sad comparing to what you can usually find online. (seriously, look to the internet for computer hardware and expect to save $$$)
$150 online could get you a high-end 9600GT (which squashes the 8600GT, and is just an underclocked 8800GT), or a lower-end 8800GT (which usually assures good performance from most current generation games).