Your computer should be set to boot from your CD/Drive first. If not you can easily change it in your bios

. You boot from the actual disk when reinstalling/repairing the XP operating system.
A repair install will reinstall your operating system over the top of the one you are using now, however....It should not move/delete any files,folders or programs you have installed. You would have to go back to the Microsoft site and reinstall any updates for you operating system though.
My advice at this point would be to perform a repair install of XP and wait until you have your new HD before performing the new install. If that doesn't solve your problems then go on to a fresh install. I left a link to performing a repair install below
http://cbttechs.com/forums/showthread.php?t=455
Just shout up if your not sure about anything :thumbs: