Doesn't have to be xp pro. It can be xp home. You just need to get the repair console running; we aren't going to reinstall windows, can't do that. As you are getting to the internet somehow, I would also recommend getting the Ultimate Bood Disk from here (
Ultimate Boot CD - Download the UBCD) and following the instructions for an ISO burn, as that will allow you to get into DOS, and once there, you need to run chkdsk /r. That should allow you to boot into windows, and once there you need to defrag immediately, as that loop is usually (but not always due to a fragmented boot area on the disk.
but the kicker is getting to dos; this is why you don't need pro; home will work just fine, just hit 'r' to get to the repair console, the admin password should be left blank (unless you've added one), choose the windows install you want to fix (usually 1) and then chkdsk /r from there. Either one will work, just need to get to dos.
Thanks,
v