Hi MattS, and welcome to BC!
Without knowing the error message from the Blue Screen of Death, it may be hard to track down the problem.
But first things first, we need to access and backup your important data.
For this, I see two options. Connect the drive to another computer or boot from a LIveOS type device. More details:
1) physically attaching your hard drive to another computer. I see that your computer is a laptop. Most laptops don't have a spare hard drive connection and most laptop hard drives won't connect to a desktop since the IDE interface on the drive is much smaller than a standard desktop interface. There are adaptors available and if I recall correctly, they're only around $15-20.
2) Is using a LiveOS to boot the laptop. A Live OS is a whole operating system that runs from a CD, DVD, or USB drive. There are a lot to choose from, most are Linux based. Were I in your place, I might usethe Ubuntu LiveCD, but that's just my preference.
There's also something called the "Ultimate Boot CD For Windows" which is a LiveOS based on Windows and crammed with diagnostic and recovery utilities for dead Windows installations. I would have recommended this one first but there's a catch. You need to have a full Windows XP SP2 install CD and a working computer to make the CD (this is because the CD has copyrighted Microsoft stuff on it which they can't redistribute, hence the need for an original CD).
Building the Ultimate Boot CD for Windows is not hard, just a pain. You can get the UBCD4Win from here: http://www.ubcd4win.com/
; your can download the Ubuntu LiveCD from here: http://www.ubuntu.com/GetUbuntu/download
Once your data is safe, we can move on to repairing or reinstalling Windows.
Reason for edit: fixed a link
Edited by Amazing Andrew, 24 May 2008 - 08:10 PM.