HP Celeron problem, please help

I have an older HP Pavillion 766mhz computer here. It is my GFs old computer and she wants to give it to her parents. The problem is this, I removed the HD and installed it in a different computer, and now I've replaced the missing HD with a new one. When it boots up, it gets passed the BIOS screen, then shows nothing but a DOS cursor flashing and does nothing after that. Anyone want to guess what I'mm doing wrong?

Note: this computer is FUCKED UP. I tried to put more RAM in it and it's set somehow to only accept 128MB, ,and only the memory that came with it. Her keyboard broke and it was very picky as to what brand I could replace it with. Plus it's a cramped little celeron. I've already cut and burned my hand working on this bastard.

Any help will be greatly appreciated.

"then shows nothing but a DOS cursor flashing and does nothing after that. Anyone want to guess what I'mm doing wrong?"

Are you sure its a good hard drive? WIll it boot to a boot disk? Is it recognized in bios?

"I tried to put more RAM in it and it's set somehow to only accept 128MB, ,and only the memory that came with it."

Did you try and add ram to the ram thats there? Or did you take the old ram out and put the new in..Yes the ram has to match and it has to be the right bus speed for your MB.

The HD should be fine, it's the one I've been using in my computer for a couple of years. The BIOS recognizes it.

Is it an HP Pavilion?

Those are brutal to work with. I've cut my hands many times. Definately designed with price in mind.

"The HD should be fine, it's the one I've been using in my computer for a couple of years. The BIOS recognizes it."

Have you run fdisk?

OS?