if you UPGRADE, which means bootup to your destop of xp home, drop in the pro disk, or start the install from windows, choose UPGRADE...it will use the drivers you have now and your programs will still be installed. if something goes wrong, like you choose new installation, a problem during install, or any unexpected happening...you need to have your stuff backed up....even if you dont do the upgrade, backup your stuff, windows is well known for it's ability to lose everything you have in seconds.
here's a link that has the basic "how to"
http://reviews.zdnet.co.uk/software/...9143760,00.htm