I've not had any problems activating XP
Updates are still 'live' ( Don't know how long for )
but worth using wsusoffline to grab all of the updates/service packs
( well worth it as you can then do an unattended update )
Note, you need the older version (9.2) for XP

Installation of an operating system is usually quite a straightforward process: simply boot from the appropriate DVD. It will reformat the hard drive (after optionally testing it for errors), partition it correctly, and install all the right stuff.

Incidentally, I am a big fan of (commercial ...) virtual-machine software, and of removable (FireWire or USB) hard drives. Today, I wouldn't dedicate modern hardware to run under XP, which is 32-bit IIRC. I'd use a more modern version of something as a host, install VMWare or somesuch (yeah, VirtualBox works, but I don't like to monkey with stuff if I don't have to), then install guests: an XP guest maybe; a Linux guest or guests.

The main reason I caution about XP is because of my understanding that it is 32-bit and my lack of understanding of whether this would limit you running 64-bit guests. Hence, I'd run (probably) the most-current version of Windows, purchased not OEM off-the-shelf on a DVD, as my host. (Or, 64-bit Linux, of course, as the host.)

XP will run properly in a VM ... it happens all the time around the world ... and it will activate correctly there. For all the mumbling that Microsoft may have about not wanting to support what is probably the most-widely-used Windows version: "heh, good luck with that."

First off, I'm sure that you're aware that Windows XP is outdated, insecure, and 99% obsolete.

However, if you're really sure that you want to install Windows:
1. Back up everything off the computer, since Windows has little or no respect to other partitions.
2. Unplug ALL flash drives/external HDDs. Open a root terminal in Linux, and run "dd if=/dev/zero of=/dev/sda bs=512 count=1" THIS WILL WIPE THE DRIVE, AND ONCE YOU HIT ENTER THERE'S NO GOING BACK
3. Shut down (you can just hold the power button if the normal shutdown command doesn't work) and reboot into a Windows boot disk.
4. Install Windows...
5. Enjoy the next few days of rebooting.

I don't think linux can wipe the drive it's currently on. Or is this just erasing the MBR?

Thread is dead
No need to keep posting the obvious.