Just for future reference, OEM keys are different from retail keys, and volume license keys like you get from computers preloaded with Windows, are different still. They are NOT interchangeable.
That said, you should consider a Linux LiveCD type distribution, only maybe install it on a USB flash drive if your computer can boot off of USB. You can use that to get at least read-only access to the files on your HDD and back them up.
I recently tried using a retail XP Home Edition disk to run a repair install on a machine originally loaded with an OEM version of XP. I tried two sets of product keys -- the ones I got using magic jellybean and the ones off of the sticker on the back of the machine. Both were rejected during activation.
I have some files on the disk that I would like to recover. Do I have any options before I use the recovery disks that I made when the machine was new (which will wipe the disk clean and reinstall all of the factory software).
Thanks for the help.