|You should be able to change the motherboard. The worst case scenario would be the need to perform a repair install. |
Your CD is a full version of WinXP with no support from MSoft and usually non from the vendor you bought it from.
While the EULA does state the OS is to be used on one PC only Microsoft has recognized that hardware fails and needs to be replaced.
One thing to mention. If your WinXP CD does not include at least SP1 you probably should perform a slipstream to the files on the CD and burn a new CD. nLite OS can perform that task fairly easily. You can also include any needed SATA controller drivers. If you are presently using a SATA hard drive then you may need to perform a fresh install because the new board will probably require different SATA drivers.
Are you planning on going to something completely new including processor & RAM?