Looking at your list of games, I see that you were once a PC gamer, if you ever intend to return to pc gaming you may as well skip the 360 and go for the PS3 as there is a lot of overlap between the PC and the 360 and PC/PS3/Wii gives the best coverage.
Alternatively you could go PC again since you could put together a gaming system with more power than a PS3/360 combined for about $500 as an upgrade to your existing machine. I see that you like strategy games and the PC/Wii combination is quite powerful. You can even plug it in to your tv if you want and use it as a media centre/gaming machine if you prefer using console type controls. Most of the sports games now are going to start coming out on the Wii anyway so you're not missing out there, and you get to enjoy most of the 360's excellent lineup + the pc exclusives.
Its basicly a - Phenom X4 9850+Free motherboard $235 (Quad core is good for strategy games) 2gb ram - $40, Radeon 4850/Geforce 9800gtx $200 so round $500 with shipping.
Tease.
