I got an old (p100) pc from a garage sale for 10 bucks.
Anyway its pretty good except the hard drive is gone, bad sectors all over it. I've got another old drive that I'll put in.

When I pulled it apart, I noticed the hard drive was tucked right up under the power supply. Do you think this could have caused the problem? Like magnatism from the power supply or something. (Its an old box, the leds on it say 33)


Should I just bung the new drive back there or go to the trouble of rigging up something in a 5.25 bay?

I have seen many machines in my early days with HDDs fitted near power supply unit. I always wondered about the same question you are asking. The answer is NO. It won't get affected by EMF of PSU, since PSU is assembled in a metal case. Dunno whether the answer/ reason I got from my seniors is correct or not but haven't seen any defect caused in hard disk due to magnetism of power supply.

It's always better to play safe and fit your new HDD in 5.25 bay.

HTH n' Good Luck !!