My hard drive was old and made some wierd noises, so I got a new Hard Drive. I put it in but didnt replace the old once so that I could copy files onto the new one. but that is not the problem. Once I put it in I tried to turn it on, the lights flashed then went dead. I've tried everything with the same result. I thought the power supply was on the fritz but I didnt think it would just die on me. The switch is wierd, it connects to the motherboard rather than connecting directly to the power supply. I dunno what the problem is. any one know what it may be?

you probably dont have an OS on your new HD

That can't be the problem. I am no simpleton here. I left the old hard drive on master and put the new one in on slave, so that I could start up the computer like it used to and then copy the files from the old HDD to the new HDD. That cant be the problem. Even so, it would have started with a boot disk when it didn't. Any other ideas?

Some things you might want to check, and then maby I can help you better, 1st remove the new HD, and see if system will boot. If the system dose not boot, dose the case fan/cpu fan spin? You said the switch is "weard" and connects to the motherboard, and not to the power supply, this is normal for AT case, the older ATX power supply's conected directly to the switch, Im thinking you might have taged you board with static, (but this is just a shot in the dark) Some more info and maby I can help better.

Oh... must be getting late...Im half asleep I think, last post I switched em, sorry, this is correct the older AT motherboards used the power supplies with a switch going directly to the ps. The new ATX motherboards use switches that go to the motherboards.