Right, i'd say go 360, mainly because the original members of TDU:C are all from the 360 side of things :p The majority of this community on consoles is on the 360, so that's got to be worth something.
On its own merits, the 360, whilst struggling with the gremlins, is a very capable console. Its base of exclusive racing games surely should appeal to you, being as TDU, PGR4, Forza and Race pro do not appear on PS3. The support for wheels is a bit lacking, though, the official xbox wheel (good wheel but rubbish construction) is the only one with proper implimention of FF, however the fanatec wheel should change that.
Xbox is getting exclusive DLC for GTA IV if you're a fan of that also. The current premiums come with the 60Gb HDD, which is brilliant, as it gives lots of room to install games, demos, save music... whatever you fancy, even download movies, which i know you love so much ;)
The controller I find is the most comfortable I have ever used, and is very good for FPS and driving, RTS are crap with a controller in generall, but the voice controls on endwar work very well. The only kind of games the controller doesnt really work on are punch-em-ups as the D-Pad is hopeless. Overall I find it almost perfect though as a no-nonsence controller, it is nicely weighted, no motion nonsence, pretty cheap to buy, has a nice place to your mic/chatpad in, and can take wall-related impacts ;)
otherwise there's LIVE which is a very very good online system which has brilliant integration with most games, and being as games for windows live is kicking off since GTA IV you can keep your friends from PC on your contacts. and ofcourse you can use winows live messenger (for anyone crossing their eyes, it's the fancy name for MSN ;))
It was a suspicion that they would replace the xbox soon, but the NXE shows they have a long term plan to keep it.