Yep, youll have to check with another power supply and work from there to look what isnt working, but it isnt the hard drive [good news to you :)]

I think is the power supply, if you do have another one around connect it in the computer just to check it

Its probably you have set up your memory card not properly, please make sure it is firmly inserted. Dont worry its a common error when you tried to build up a pc :). The most common problem is...

i suppose you can get a windows xp cd and get to boot from the cd then select instead of installing, the Windows Repair thingy and it will open DOS for you, in there type HELP and look for a command...