If you are talking about a prebuilt system there with the included recovery disk forget it. Swapping boards is a major hardware change requiring a fresh install of XP and you can expect that with Vista too. The recovery disk is more or less bound to the original hardwares seen in a prebuilt system. Sorry to say but you will need a new copy of Windows full version preferred to start fresh there.
The drivers for the existing board and included hardwares are safely stored in a hidden portion of the drive to allow for recovery with the disk you have. For a new board buy an OEM release of XP for under $90 by shopping around.
Which version of XP are you running? One place saw XP Pro/SP2 for $80. The OEM I'm referring to isn't bound to one machine but simply lacks the retail carton and large paperback book. It simply gets shipped in a mailer with ot's original sleeve for the disk. Vista is larger is seen on dvd in a plastic case. But you save there rather then spending closer to $200 for the carton and book.
One place found with the lowest price on XP Home/SP2 is at mwave.com. The price there was only $82.99 as seen at http://www.mwave.com/mwave/Skusearch.hmx?scriteria=AA15060 Here I bought both 32bit versions more then once plus have a multiple boot going with Vista Home Premium. That's why I build my own rather then being limited as far as OS options.
The drive is no problem. But the problem with only having the recovery disk provided for a prebuilt system is not being able to perform even a good repair install of Windows. With a new disk you can easily delete the current installation to avoid wiping everything you have in other then MS created folders namely Windows, DocumentsandSettings, and Program Files.
Or you can backup everything and simply start fresh after removing the hidden partition meaning finding and removing that with a drive partitioning tool and stretching the current primary or deleting everything to create a new single primary. As long as the drive is still in good working you simply decide which route to take there.
Just to clear things up, it will replace program files documents&settings or it won't?