You must have another PC .... so ....
download sp2
http://www.microsoft.com/downloads/details.asp x?********=049C9DBE-3B8E-4F30-8245-9E368D3CDB5 A&displaylang=en
you need it anyway ... so .... might as well
then download Nlite
http://www.nliteos.com/index.html
use it to create a new "slipstreamed" install CD with SP2 already included
(this is quite easy ... just follow the instructions! - it even creates the CD for you)
If you feel like it you can also include all the updates since SP2 (this saves lots of time in the long run)
http://www.ryanvm.net/msfn/updatepack.html
while you are doing all this downloading ......
look at the quick start guide for your new mobo
(which is it btw?).
does it say anything about needing SP2?
either way .... personally I'd start again and re-install XP from your new shiney XPsp2 cd
then use the mobo CD to complete the job