Upgrading from XP Home to XP Pro is probably the easiest and most
reliable of all Windows upgrades.

The core components of the operating system will be unchanged, as
these elements are identical in the two versions.  All that needs to
be done is to add the relatively few components and functions that are
found in XP Pro and which are not in XP Home.

And after the upgrade you will have to redo all of the Windows
updates.

Before spending the money for the XP Pro Upgrade you should make
certain that you actually need at least some of these few features and
functions that are only in the Pro version.  See the following web
sites for details of the differnces between the two versions:
http://www.microsoft.com/windowsxp/whichxp.asp
http://www.microsoft.com/windowsxp/home/howtobuy/choosing2.asp
http://www.winsupersite.com/showcase/windowsxp_home_pro.asp
One additional item that is not mentioned on these sites is that in a
peer-to-peer network sharing situation XP Home allows only 5 logins
whereas XP Pro allows 10.

Good luck

Ron Martell     Duncan B.C.    Canada