Forgive me for sounding a bit thick but if aa2239's computer is failing to even power up let alone start the OS then what diference does it make what OS he's got on his hard-drive?

Sounds to me like a nackered PSU or failing that......

Have you checked the fuse in the plug? You'll be amazed how many people forget that small but very important part of a pc or indeed any electrical item.

Smirnoff