Please answer ThorXP's questions, we'll give you the instructions for a retail installation and a retail install CD, but they won't work with an OEM operating system (preinstalled by the manufacturer, usually on brand computers) and they won't work with a laptop.
Tell us more about your system specs, you'll need to reinstall all your drivers once Windows is installed. What's the brand and model of the computer ? If it's a custom build then check the "posting system specs" link in my sig.
If by clean copy you mean format the drive (you'll lose everything that's on the hard drive so make sure you've backed up your data on another physical drive) and reinstall from scratch then you can do that with your plain XP CD. Make sure you use the CD that was used originally to install XP on that computer (or double-check that the version corresponds to your product key).
Boot on the XP CD (enter the BIOS at startup and change the boot order priority to CD-rom first) and press enter to setup Windows now. Accept the licence and don't choose to press 'R' to repair the selected installation. Instead delete the existing partition, create a new one and reinstall.
You shouldn't get an error message about the version of XP but if you do you can either :
- wipe the drive with a dban
floppy or CD so that no traces of the previous operating system are left when you start the installation process
- create an XP SP2 CD
and use that CD to reinstall.
I would advise you to use an XP SP2 CD anyway, it'll be cleaner and will take less space than installing XP then SP2. You could also create an XP SP3 CD
right away, but you'll need to start the slipstreaming process from the previously created SP2 CD or from an SP1 CD. You can't slipstream SP3 on an pre-SP1 CD.
If you had a virus on that computer I would use another computer to create the XP SP2 or XP SP3 CD. Make sure you run a complete virus scan on the backup before restoring your files on your computer.