Hi,
It's simple. Just buy a XP Pro CD, boot from it and
perform a inplace upgrade of XP Pro.
1. Boot into BIOS and change the boot sequence to CD-rom
be the 1st boot device. You can skip this step if your CD-
rom has already been set to 1st boot.
2. Insert the XP Pro CD into the CD-rom and press
Ctrl+Alt+Del keys to restart the computer.
3. After the computer finishing POST, watch the bottom
line of the display, when prompted to "press any key to
boot from the CD" appeared, press the space bar
immediately to let it boot from the CD. If you missed the
chance to boot from the CD, restart the computer and try
again.
4. The setup screen appeared then press the "Enter" key
to enter setup.
5. Press the F8 key to accept the licence agreement.
6. When prompted to press the F6 key to install 3rd
party/raid drivers, don't press the key unless you need
to install those drivers.
7. DO NOT select delete existing OS otherwise all the
data files in C drive would be wiped out. Press the "R"
key to select repair install of XP.
8. Follow the prompt to complete the installation.
9. After XP Pro loaded successfully, all the data files
and applications should be safe. Update the windows
patches from windows update site.
However, it is the best practice to backup all the data
files before changing the OS.
Hope it helps.
Peter