I always forget about this when I’m reformatting my computer, so I thought it might be nice to post it somewhere that I (and you) can find it somewhat easily.
For the time being, XPize does not properly patch uxtheme.dll to allow custom visual styles in Windows XP SP3, though XPize v5 is coming out soon, and that might change.
Here’s the link to the new uxtheme patcher called UXTender:

