the OS not working i would understand, if it was installed with different hardware it would not be usable, but it shouldn't give you that error... there's a long list of others you should have encountered.
Is there any way you could post a picture of the pin connectors on the hard drive? and/or the plug in the laptop. If they were bent or corroded it could prevent the drive from being read properly.

also can you enter bios before it gives you the error? if so check to see if it recognizes the drive, it isn't an answer yet, but it will limit the options i have left to give :)

*There are many things that can be tried if there is a way to get the cd drive to work at the same time the hdd is in.

The HDD that was in there before was 80GB, the one she gave me was 30gb. My old Dell can use it, it reads it and I installed XP on it with that. The Compaq says "No IDE Device" when I do the Hard Drive Self Test in BIOS.

it read the other HDD that was in it, but that HDD was broken, it happened to her between college and her house. It worked fine there and when she got home it didnt work right anymore.

Ill ask her for the old HDD and see what that says when I plug it in.

That one it did recognize and the CD/DVD-Rom worked with it. This new 30gb one, it doesnt read, nor does the CD/DVD-rom work...

Its probably something simple, like conflicting HDD or something...:confused:

I just got off the line with the compaq help line, they suggested going to a store and having them put in a different hard drive. They said this is what I need for it to work correctly.

gary: Below is the partnumber:
gary: 319414-001
gary: 40.0GB ATA-100 EIDE hard disk drive - 4,200 RPM, 2.5-inch form factor, 9.5mm height

Any comments?