Which game "sucks you in" more?

I have 1200 MS points and am thinking about spending them on one of these games. I don'thave xbox live goldbut I occasionally playwith my friend when he comes over. I was thinking about gettingCC but I still have doubts that the multiplayer will increasethe fun factor since I won't get to playthe multiplayerevery day.Which would you say has the better single player/gameplay?

OK thanks for the antivirus info. Can anyone answer my other question? Will I still have that virus after doing system recovery? Thanks for helping.

I have Vista by the way. My computer recently became infected with a virus(I am pretty sure it was a trojan). So I did a full system recovery(press F11 at startup). So is it still possible to have that virus at startup? Also, what are some good antivirus programs? Free antivirus programs would be great. Thanks, help is appreciated.