You should not lose anything when upgrading from XP Home to XP Pro. The only thing that might happen is some settings might be changed (i.e. java being enabled on your web browser) or something like that. One problem I have found when upgrading from XP Home to XP Pro is that sometimes your drivers to certain hardware do not respong properly to the upgrade. I recently tried to upgrade to XP Pro and the touchpad mouse on my laptop stopped working. There was an updated driver online but its just something to think about.