Simply put, your motherboard drivers are totaly wrong. You are going to have to do an in-place repair of windows in order for you to be able to access your data and OS. What you will have to do is boot your new computer off of the windows XP CD, and go through the install process carefully. When you get the first question asking you if you want to repair XP click on no. It will ask you a 2nd time a step or two later. (It's been years since I have had to do an inplance re-install, but I do know it's the 2nd time you are asked to repair windows that you select yes) Select the Repair XP installation at that point and that will do what is called an in-place re-installation of windows. It will force windows to re-detect all the hardware and install the new drivers. Just make sure you NEVER select to format the drive in any way, or delete a partition.
Hope that helps you out.