I've seen a few comments that SP1 or SP2 is a prerequisite for slipstreaming SP3...but I've also seen references that just say XP CD. It won't hurt to try, the cost of a coaster is negligible.
The download for SP3 itself is 300+ MB...but some of this are updates that have already been included (files replaced) at prior times for those who have SP1 or SP2 installed. So, my slipstreamed version of XP is about 595 MB, I think.
Edited by hamluis, 23 June 2008 - 06:47 PM.