Not all releases of XP come with SP1. Only releases cut after the release of SP1 came with SP1 included. If you reinstall with a pre-SP1 disc, yer gonna get a plain XP installation.
Standard USB is 1.0, which comes with regular XP. If for some reason you NEED 2.0 before you update to SP1-2, you can simply download the 2.0 drivers from the web and install them manually. 1.0 will work with most things anyway, it'll just be slower.
Also, last time I checked, you can no-longer upgrade to just SP1. SP2 is the current service-pack, and if you update Windows you get the full update. (If you have SP1 on a CD or something, then you can update to SP1, but you're not going to get full support for it, and the MS update sight has all but cut-off support for SP1...though you can still find a temporary archive connection for SP1 if you look around. Don't expect that for long, though. It's getting cut.)
Besides, it's not worth remaining in the past unless you have a fatal issue.