I know what you mean. I sold my slim, but I still have an older box. I thought about selling my intstruments over Spring Break, but it is going to be hard to want to part with them. I can't think of anything aside from Gears 1 that I enjoyed this generation as much as RB. I think I bought something like 4 or 5 hundred songs over the lifespan of that series.
Yep, I have around 300, and even though I haven't played the game since a couple months after RB3 came out, I can't bring myself to part with all of that. It was definitely the game(s) of this generation for me, hands down.
If I keep the HDD, all of that stuff will work on another 360 right? Maybe I'll just keep it and if I want to I can buy a cheap box down the road for some nostalgia...
In other news, Willy Wonka and the Chocolate Factory is on AMC.