I recently aquired a homebuilt, (used to be Gateway), P3 550, with 256 Meg of ram. Original HD was 10 gig, with DVD player, and Win XP. I saw this machine running. It seemed fine. I brought it home and had trouble ever since. First, after removong the orig HD, I added my 2 HD's which already had XP loaded, and ran just fine but power supply went out. Then I added my CD writer, leaving the DVD player. I checked all of the jumpers. HD's are on primary, master & slave, and CD writer is secondary master, and DVD is sec. slave. The BIOS sees all componants.
On boot up, I have to boot from the XP CD. System will not see the OS. OK, so I tried reloading the OS. Went as far as deleting partition, and formatting to ntfs. After formatting is done, I get a message that windows can not be loaded on this drive, and that it could be damaged, to try another partition. I always get the same message, even after trying different drives. I also tried a different, known good cable.
Any suggestions?
Please help.

here's a couple of sugestions:

install the problem drive into a different computer and try to install the OS. If it installs that proves the drive is good and the problem computer should be tested for faulty memory.

If the OS does not install, start the recovery console from the OS cd and run chkdsk with the /p /r switches(not sure if the /f switch is in the recovery console if it is use that) and check the drive's manufacturer website they usually have diagnostic tools that you can download to test the problem drive.

hope this helps

Did you try switching the HDD's to secondary and the CD/DVD to primary IDEs? If it's a problem with the IDE controller it wouldn't matter if there the cable was good or not.

Did you try the windows disk in both drives? sometimes a bad drive can mess up an installation, or a bad cable to the optical.

Did you try taking the extra components out and running it at it's original configuration? This would help narrow the problem down to configuration or hardware, and which hardware it is.

I don't have another computer to try the drives in. I did try multiple drives, and I did try putting everything back to the original working configuration that was in the PC when I first got it. This made no difference. I did try the OS recovery. It brought me through the same senario including format, then dumped as before. I will try swapping the primary and secondary IDE's. Didn't do that. Thanks toi all for your help.

can you post the exact error message that you get? also you can download the ultimate boot CD and burn it to a CD then boot the computer with it. this CD will allow you to test the CPU, memory, and the hard drive. It also has other useful tools. Or if you have the money to spend buy Pc-check by Eurosoft. Its a very good piece of diagnostic software.

Ultimate Boot CD

Pc-Check by Eurosoft