I had 1 game the day I bought the 360... then the very next day I bought 2 more
yeah oblivion is one of the best games for the console, but I can completely understand why you'd go for the PC version over the 360 one. As for me my PC is getting close to 3 years old now so... it'd be hard pressed to produce Morrowind era graphics.
I've really enjoyed PGR3, PGR3 and DOA4 where my two biggest reasons for getting the console.
Condemend is an awesome game as well, some say it's a bit short but it takes about 15-20 hours a play through, and I played through it twice. You can get a used copy for under $30 if you look around, I want to say BestBuy dropped their new price down to $45 or $50 IIRC. Probably my favorite game for the console so far.
You could always sign up for a rental service. $20 a month and you can have 2 games at once. That works out the the price of a new game every 3 months and you pretty much have full access to all the titles availalble.