Online really isn't a must for me, but it would be a nice add-on. (Xbox Live)
I don't have tons of money, so I would probably be buying last-gen games for a while (lots of great xbox fps games + fable/KOTOR1&2/morrowind etc)
Custom soundtracks & Ipod connectivity for games is great. + You have Mass Effect coming out in November - The Darkness just out - Halo 3 - Bioshock - too human etc...