I only have one XBOX and it has been 8 months since I bought it. It is still in good condition haven't encountered any problems as for now I really hope it will stay on that condition forever.
I am using my XBox for more than a 6 months and still I haven't come across any sorts of problem. Even my friends too join me and it will be on load at-least five to seven hours a day, but still works pretty well for me.
My had lasted 7 years for the original xbox system. I think that it is longer than normal for a gaming system that is used frequently. I think there is only a soldering issue that is wrong with it. I think I will try to get someone to take a look at it and see what we can do.