Well, I really can't tell from your description what exactly you have done. Are you trying to put the hard drive from the broken computer into your other computer as a second drive? Is the XP OS your current operating system in your Working computer? or is that from the broken computer?. If you can't see the drive in the bios, there are several possibilities. How big is the drive? How old is the computer you're trying to put it into? If you're adding it as a second drive, you probably need to reset the drive jumpers on the drive itself to clear a conflict. If it's a big drive and you're putting it into an old PC, your pc's bios may not be able to read drives that big. Give more specifics, and perhaps we can give you more explicit answers.

The hard drive is an 80gig and yes-it is going from the 'broken' computer to the one I was using before getting the 'broken' one.
Trying to put it in the computer as the master drive and I have that connected correctly. I hadn't thought to look at the drive switch. Will do that when I get home from work.
It is a drive that was never in the 'old' computer. I had a 40 gig in there.
The 40 gig was 'ghosted' over into the 'broken' one- and then we decided to go with an 80 gig that my buddy was selling. So he came back into Lansing and 'ghosted' again from the 40 to the 80 and put that one in the 'broken' computer.
The reason for switching out hard drives(as well as the dvd and cd-r) is that there seems to be a serious problem with the 'broken' computer as far as video goes. I never had a problem with the video on the 'old' computerand was beginning to think it was the video card-bought new video card and still have problem. I get the 'no video connection' symbol onscreen and then nothing-no bootup( I do get the choose 'last known good config, safe mode or normal' option for boot up-no matter which I choose I get nothing). Anything else you need to know please ask. Not sure what other specifics you might need and this is probably already getting too 'windy'.

OK, so you're swapping a 40 to a 80 gig drive. I still don't know how old your "old" machine is, but it probably is just incapable of reading a drive that large. For some of the "old" machines you can get bios updates that will allow it to read larger drives. Also you can get IDE addin PCI cards that will allow you to read larger drives. If you know what you have, you can get the information from the board manufacture's web site about how large a drive it can handle.

I'm not real sure how old it is. It was a system that my husband put together and has been working GREAT for the part 3-4 yrs.

Not bad for humans, but "Long of Tooth" in computer years!

ok-thanks for the help.
If I can find the spec sheet on it that'll probably help.
In the meantime will see if switching the drive switch helps at all.

Check the jumpers on all Hard Drives they should either be in Master/Slave mode or cable select. Check with the HDD manufacturer for the jumper settings.

did you try and install a fresh copy of your OS?
that includes reformating your drive.

Haven't tried installing fresh copy of OS yet. As to the switches, they should be in the master position but will check to make sure. I did find that I can boot the system into safe mode but not in regular mode. I tried 'last known good config' and it wouldn't boot. I tried a restore to the previous Sunday(a checkpoint) and still only can get it to boot in safe mode. I was able to check 'disk management' and it does 'see' the hard drive and says it is healthy'.
I am going to try a fresh install-before I do-what would be the best way to copy my pictures before I do?