[arsenal]

Swapping HD's could cause a problem. Every time I have tried swapping HD's from seperate machines, it seems to cause an issue.

Actually, you are pretty much home. Probably the easiest thing to do would be to back up all the important stuff on the machine (using your fancy new DVD RW), and whipe the hard drive.

But before you do that, buy a motherboard that will accept the P4 2.5 processor, will fit in your case and has an AGP slot. Make sure the AGP slot on the motherboard, will accept your video card. AGP cards are either 2x, 4x, or 8x. So, just make sure the AGP slot is compatible with your vid card.

Steps would be:
1) Buy a new motherboard that works for you
2) Before installing the new motherboard, back up all your important stuff on to DVD using the current work pc.
3) Open case up, swap in the new mother board, that means putting in the CPU, Memory, DVDRW, hard drive you want to use, Vid card, sound card, etc.
4) Close everything back up, turn pc on, put in Win XP CD, boot from CD, and re-install windows.
5) Re-install everything else.

I know it sounds like a huge pain, but it will keep you from having headaches in the future.

At least thats what I would do.
Others might have a better idea.

But HTH anyway.

edited for clarity