in
If I install a full version of Windows XP Pro over and existing installation
of Windows XP Home Edition will it completely overwirte it or will it give me
the option to just do an upgrade.
You will need to use a retail version of Windows XP Pro to do the
upgrade. OEM versions wipe (format) the partition to lay down a fresh
copy of the OS; that is, you cannot upgrade using an OEM version. So
decide if you want to spend more money on a retail version of Windows XP
Pro or if you are willing to move your data, configuration, and other
files to somewhere else, do the fresh OEM install, and then bring back
your files. With the OEM install, you'll have to reinstall all your
applications. With the retail version, the current applications should
continue to work but you'll pay more for the retail version.