My recovery disk that came with my pc is locked to the BIOS on that motherboard I believe and so will only work with that board, if I put the disc in another machine the content will not show up. Yours may be the same so it might not work.
If you have a folder named I386 on your hard drive (do a search for it) then this page click here explains how to create your own windows disk from those files.
I ment to add that yes windows will still try and load but as you say for a clean start it will be best to reinstall plus the fact that xp might want you to reactivate as it does when you make any major hardware changes.
Be sure to clean off all the thermal paste on the CPU and the CPU heatsink and fan and renew it, if don't do this you can have hotspots which will blow the processor. If you haven't already bought your motherboard you could by an OEM copy of XP with it for about £60, I mention this in case your copy of XP will not install on the new motherboard.