I have used Seagate disc wizard software in the past to get these drives to work. Do know if that can cause any of these problems?

On one cable one master and one slave,set the jumpers
If you want to install Xp,set the BIOS to boot from cd/dvd,put the xp disk and first format the partition with NTFS,cause the xp needs it.If you want to format the 3 Gb harddisk too,then format it the same file system (NTFS)

A computer that is that old absolutely will not be able to handle the cable select option. You need to set one as master and have it on the very end connector of the data cable and the other set as slave and on the remaining connector.
You should also update the bios to the most recent version as it's original bios will most likely not be able to read any hard drive greater than 27gig.

I have not been able to find the correct bios. HP shows this 3.07 as what is needed for ME or XP, but it doesn't work and I haven't been able to find anything on the Cognac Motherboard (200731). I hope someone knows more than I do.

Have you tried a bois reset by removing the power and the CR2032 bios battery for a while?

I have never heard of it. Where do I find this battery?

OK I found the battery and now have it out. How long does it need to stay out?

1 minute will be good. Make sure the mains power is unplugged too.

Thanks for all the help, but I found on Microsofts website that I when the XP installation says to push F6 that with Pavilion 7840 you are supposed to push F5 instead and then select Standard PC. All is well now. Thanks again for everyones help.