I have an HP here with a 300 GB hard drive. I reformatted it to original factory state using the HP restore CD. Many of you may already know that alot of manufacturers automatically create a 6-10 GB partition with an image of the restore CD (so if you lose the restore CD, no need to worry about it). I'm trying to upgrade the Home XP to Professional XP and I went through the CD boot, basic driver installation (on the blue screen of XP), and at the installation window, it gives me an option to either format or already write on the partition. It says the documents and everything will be erased if I install without formatting, but some people said that you can upgrade it and all documents and software will be there, only the system folder will be upgraded. Anyone ever tried this? Can I upgrade without losing any data? Another question: Since the hard drive has 2 partitions, the system keeps booting to the partition with the image of the restore CD...how the heck can I make it boot the other partition with Windows? I tried everything.

While you should be able to install Professional XP over XP and not lose any data, you should absolutely back up your data. If it were me, I'd back up all the data and just do a full format of the drive and the install Windows. Cleanest way to do it.