Don't tell me.... your Xbox 360 is out of warranty and you have started having problems?  How many times does this happen with our stuff at home?  First of all DON'T PANIC!  

Have a look at this and fix it yourself like we did, I promise it is pretty straightforward with easy to follow instructions, so if like me, you are not a technical wizard, don't be put off!
Xbox 360 Three Red Lights Fix