Hawkeye22 :
Do the article numbers correspond to the KB number? If so, just grab updates above the last SP3 article number (950749).
I believe the article numbers do correspond with the KB numbers. However, the problem is you can't go by those numbers because they are out of sequence - that is, they don't follow chronologically. It jumps around randomly.
For example:
Update for Windows XP (KB952287) Release date: 5/12/2008
Update for Windows XP (KB944043) Release date: 5/26/2008
Update for Windows XP (KB951830) Release date: 5/26/2008
Update for Windows XP (KB932823) Release date: 5/27/2008
I suppose I would need to know what the cut off date is, and then download everything after that. I did find a few lists by searching the internet. The trouble is, I think Microsoft may have revised and changed things since those lists were compiled.
It may not be worth it to try to slipstream the post SP3 updates. I might just include SP3 on my disk and then let the automatic updates grab the rest of them since SP3.