Use a boot floppy or CD ROM (make sure computer is set to boot from CD ROM before HD) if you use the CD ROM. Format and partition the hard drive and you will be good to go. I am really surprised that you had Win XP Pro installed on a 6 Gig HD, or do you mean that you are putting in the 40 Gig and installing the Win XP Pro OS? I am not familiar with your Creative Board, but if it only had a 6 Gig HD, I will have to assume that it is really old. Win XP does have system minimum requirements and your system may not meet these requirements.
3 different OS, so yep I\'m confused.