I'm on 360 number 3!! No problems with this one so far
My first 360 had a cooling problem, which was replaced...
...the second one was fine, but I got rid of it when the PS3 was released purely because it had the blu-ray drive.
It's a great all rounder (even though it looks a bit like a George Foreman grille

) and the blu-ray player is obviously a massive plus point!
However, I rarely used it to play games (GTA was about it) and it was used mostly to play blu-ray movies.
Once the stand alone blu-ray players were down to reasonable price, I decided to get rid of the PS3 for a 360 elite and get stand alone player for blu-rays
I've not looked back since! There just seems to be better choice of games on the 360 (Gears of War 2 and Fable 2 recently, not available on the PS3)
I'd forgot how good it was online too!
In my opinion, the 360 is better for pure gaming!