Have a look here for future reference Beep, but without the disk your goosed.

Replace Motherboard on a Windows XP System

I managed to find my Windows XP disk! Unfortunately, I'm now even more confused.

I started up with the new configuration, booting from disk and followed the instructions in the link you supplied, Wolfeymole, but it was unable to find any existing installations of XP on the hard drive. I restarted again, attempting the recovery console option, and bootcfg also couldn't find any installation. I set up my old motherboard and the necessary hardware again and started up and it booted into windows without any problems.

Does anyone have any idea why the new set up wouldn't be able to see windows? It's giving me the screen with the option to start up in safe mode but then rebooting after I select any option at that screen. I assume this means it's found a windows installation but I'm not sure. If you can think of anything really stupid that I might be doing or missing, please do suggest it. I've got some experience in programming in a few languages, but I've got no experience in hardware at all (except for the bad one I'm currently going through). Maybe there's an option of creating a boot disk in the old set up and using this? No idea what a boot disk is capable of or whether it can help at all, but I'm hoping someone here knows.

Thanks again for all your suggestions. If nobody can figure out any way to get around this, I'll just have to go back to the old set up, back up files and any exe's I can find and then reinstall from scratch. Your help and advice is very much appreciated regardless though.

This is indeed strange Beep
Let me have a sniff round on this for a moment.
Well Beep I can't see anything else on this.
It's definately a full on version of XP and not recovery yes?
Were the IDE cables secure?
Unless someone can come up with a solution more or less now then I would suggest backing up what you can and doing a new install from scratch.

It's definitely the full version because I installed it from this disk originally. The hard drive IDE cable is a bit old now, so it might be worth getting a new one and trying that. It works on the old motherboard though. Maybe I'll try attaching the hard drive with the IDE cable from the CD drive. Are they the same other than the colour scheme?

Well you could set the hdd on the end of the IDE as Primary master and the cd in the middle as primary slave making sure the jumpers are set to their respective positions.