No, I don't think that right after you slipstream SP1 into XP on the HD that Windows would do anything with the files. It never did when I did it and it shouldn't need to as all of it's working files are within the Windows folder. Now if you put the XP SP1 on your HD in your Windows folder (for some crazy reason), then there might be a problem, but from what's stated above, I can't make anything out yet. More information is needed.

Oh and Ben, did you get my email a couple of days ago, about the temp access to my pic hosting site so you could link the pics on the Screenshots page? Let me know if you did or not, so you can finish that page!
EDIT: If you need any help with the HTML, let me know and I can take a look. It should be pretty easy adding the links in there, but then again, maybe it's just IE making a mess of your perfectly fine code.

Just email me if you need anything.