.. Will it cause me any major headaches? For instance, I'm going to rebuild my computer to be more modern spec. New mobo, PSU, CPU etc. However I don't want to go through the rigmarole of reinstalling the OS and all my software once I'm done so I'm just going to keep the HDD on the side while rebuilding then plug it back into the new system on completion. Though I have built many computers I've never done this before. I've always built them with a blank HDD and installed everything freshly. So I'm unsure on the side effects. I know I must uninstall any specific drivers before I proceed, like the chipset and graphics card drivers among others, but other than that I'm wondering if will be able to "adjust" itself to the new system without any problem?

Usual result is a blue screen. Different Hal. Run a repair install of xp to update the drivers. You will need to re-activate xp.

Your best solution may be to slipstream SP3 (if not already part of your CD) and The SATA, chip set and network drivers using nLite OS. Once you do that you would use the newly created CD to perform a repair installation. That would keep all your programs in place. Installing WinXP onto state of the art hardware will require drivers that are not included in WinXP. Slipstreaming is a process to add those drivers and the latest service pack to your existing WinXP files located on your current CD. Look at the links below to learn more about slip streaming and nLite. http://www.winsupersite.com/showcas... http://www.nliteos.com/ http://www.nliteos.com/guide/ http://www.nliteos.com/faq.html You would create the new CDR BEFORE you dismantle your old computer. All this assumes you have a full version of WinXP (OEM or retail).

Excellent response by OtheHill, as always :) Just to add...when you do the repair install, you will lose all updates that you've accumulated over the years. These will have to be reinstalled by running Windows Update.

Consider making a ntbackup of the drive before you attempt it if you need data and applications saved just in case. Read this http://support.microsoft.com/kb/249694 Playing to the angels Les Paul (1915-2009)

Thanks for the responses.