>My XP Pro box boots to FAT32. There is an option to convert to NTFS. Will that change anything? For example - I boot in now without needing to log in. Will I have to change the way I use the system?

It will change things internally, much for the better in general, except wrt sequential forward access in a file. It will not force you to log in (the same registry things will exist) but much finer granularity of access control can be given if you want it, and additional attributes become available. The NTFS structures are somewhat larger than the equivalent structures used by the FAT volume, but there are some tremendous advantages AFA reliability and recovery, and in fact, you may experience some improvements in terms of slack space based on smaller cluster sizes, and the fact that small files may become much faster to access, since they might actually live in the NTFS index nodes themselves rather than in separate extents on the volume.

From your perspective as a user, it won't make a big difference as far as your apps and administration, as long as you aren't trying to use third-party tools that understand FAT32 but don't know NTFS from Adam.