Seeing as I completely reformatted my MacBook Pro's hard disk, I also had to reinstall Windows via Boot Camp 3.0 today. Everything went well, however when the time came to install Service Pack 3 (my copy of XP is an SP2 OEM disc), I received an odd error I had never seen before:

An error occured while copying file osloader.ntd.  Cannot copy file to destination directory.  Click Retry to retry the operation or click Cancel.

A Google revealed that this error is caused by an Apple's new HFS+ drivers for Windows, as detailed here. Simply following the instructions and renaming the driver fixes the problem. After installing SP3, I restored the HFS+ driver to it's original state and all is well.