Failed Hard Drive

A few days ago I turned on my Dad's computer and after a long display of the Dell logo a black screen came up with the following message:

Invalid Boot Diskette
Insert a Boot Diskette in A:

I went in to Boot sequence and made sure it was booting from the hard drive first, and it was. I tried using a Windows XP restore disk to repair it, but after a few tries i got this message:

Cannot boot from CD - Code 4

The CD is an original windows CD and NOT an image or anything, and I know that it works from trying it in my own computer. I tried using the HD on my computer just to see if it would boot up, but my computer only accepts SATA drives. His is a PATA drive. Is there any way to set up a slave drive on my computer using the IDE cables that I use for my CD Drives? I have the 5 prong power cables also. Everything seems to be in place to do it but all my attempts have failed. Or does someone have a more practical solution?

Both computers are XP and mine is SP3 I believe. His didnt have any SP on it I don't think.

Please help,
Chad

Update: Even with all other devices disabled in the Boot sequence the HDD will not boot. With everything except the CD Drive disabled the CD still wont boot. Is it possible that both the HDD and the CD Drive failed? It's been off for about 6 months so I guess its possible. I even took everything out and cleaned everything to make sure dust buildup wasnt causing any problems.

Still no solution....