Slipstreaming 'slips' these new bits of data from SP1 into the 'stream' of data that the original CD provided, effectively merging the two into one XP Installation CD ROM. A slipstreamed CD is used just like any other Windows installation CD.It worked for me and saves time. Everything you need is here.
http://www.theeldergeek.com/slipstreamed_xpsp1_cd.htm