I am installing with SP1 simply because I don't wantSP2 and all of its included fixes and the problems they cause with various programs. Yes, I have the SP2CD.
With SP2 you don't have the ability to repair/or reinstall win XP and I want to have that option in the future.
see PC Magazine article:
"Build an XP-SP2 Recovery Disc"
http://www.pcmag.com/article2/0,1895,1750662,00.asp