Hello. A little while ago I purchased a Compaq Deskpro 4000 to use before I build my own pc and I have purchased a 40 GB Seagate barracuda HDD. When I hook the cables up to my new 40 GB HDD and Boot up the pc I get an error stating "1790-Disk 0 Error". Now I was curious to as if the HDD was obsolete so I had put it in my other pc to test it.... and guess what? It worked fine. I installed Windows Xp and was using it fine. Then when I had put it back into the Compaq...BANG 1790-disk 0 error. If anyone has any information at all as to how to fix this stupid annoying error, then please help me!

Not as obsolete as the computer.
Old Compaqs and IBM's stored the bios info in a small partition on the hard drive. (non flashable bios)
The info on the 40gb drive isn't there and that's why it won't boot in that deskpro 4000. It isn't capable of seeing the drive without it, hence the "disk 0 error". You need to go to Compaq's website and download both the F10 disk utilities and the latest rompaq for that system. It's a pain in the neck but it's the way they were designed. Your only other way around it would be a HD controller card.

Haha. Nice but could you give me some links, because I think maybe the hp site is so crappy that the file servers are down

Actually, that's about par for that website.
Go Here, select "download drivers and software" then type deskpro 4000 in the box and click the double arrow next to it. You will be presented with the 24 different deskpro 4000 models below


Compaq Deskpro 4000N Desktop PC series

» Compaq Deskpro 4000N Desktop PC 5166MMX
» Compaq Deskpro 4000N Desktop PC 5200MMX
» Compaq Deskpro 4000N Desktop PC 5233MMX

Compaq Deskpro 4000S Desktop PC series

» Compaq Deskpro 4000S Desktop PC 5166MMX
» Compaq Deskpro 4000S Desktop PC 5200MMX
» Compaq Deskpro 4000S Desktop PC 5233MMX

Compaq Deskpro 4000 Desktop PC series

» Compaq Deskpro 4000 Desktop PC 5100
» Compaq Deskpro 4000 Desktop PC 5120
» Compaq Deskpro 4000 Desktop PC 5133
» Compaq Deskpro 4000 Desktop PC 5166
» Compaq Deskpro 4000 Desktop PC 5166MMX
» Compaq Deskpro 4000 Desktop PC 5166X
» Compaq Deskpro 4000 Desktop PC 5200
» Compaq Deskpro 4000 Desktop PC 5200MMX
» Compaq Deskpro 4000 Desktop PC 5200X
» Compaq Deskpro 4000 Desktop PC 5233MMX
» Compaq Deskpro 4000 Desktop PC 5233X
» Compaq Deskpro 4000 Desktop PC 6180
» Compaq Deskpro 4000 Desktop PC 6200
» Compaq Deskpro 4000 Desktop PC 6233MMX
» Compaq Deskpro 4000 Desktop PC 6233X
» Compaq Deskpro 4000 Desktop PC 6266MMX
» Compaq Deskpro 4000 Desktop PC 6300MMX
» Compaq Deskpro 4000 Desktop PC 6333

Select your model, select your OS from the following page and you're there.
The rompaq will be under the "bios" heading and the utilities disk under "utilities"
Read any and all footnotes for exceptions to certain systems when it comes to the utilities disk.