Updating xp home to pro
If you want to upgrade from Home Edition to Professional Edition and you don't want to do any re-installation of any of your programs, then you cannot use the OEM edition, because you would then need to start from scratch.
Only the FULL edition will allow you to do a simple upgrade from your existing version, and then since you are only upgrading from Home to Pro, then you don't have to worry as to whether your programs are going to work or not, like you would have to worry if you were making an upgrade from XP to Vista, or 7.
This would bring up a Chipset Driver issue plus machine device driver issues also as you are probably attempting to do this on a laptop with no floppy drive. I think it would be a better idea to learn and run Linux as a dual boot O/S. I love it and have had no problems, except to reinstall all my programs.
If I install Professional on current computer will I still retain apps like Microsoft Office, etc., or will they need to be reinstalled?
Since SP-3 was released, there have been may be 400 updates or so. Is that possible morcomp, You could do that BUT honestly would be more work than it's worth in my opinion. I think you are correct with your comment about XP.
Some are in your machine and are needed and some may not be needed for XP professional. The only correct way to install XP Professional would be to make the SP-3 sliptream and then do a Clean Install and then install all updates again. XP is a dead-end O/S and your XP Home Version doesn't lack many additional features that XP Pro will give you. I have a laptop which I bought with Vista and then made a clean install to Win 7 Pro.
For that reason, on my desktop computer, I'm still using Windows XP--even on my brand new one.
I have a laptop that I bought last year that I might use an UPGRADE version on it, because I'm only going from one EDITION to another.