If the most important thing is getting your data off the drive i would pull the drive and put it in another system,
It is probally most likely an IDE drive, so you will have to have your Master and slave selections correct, (the drive on the end of the cable should be set to master and the drive in the middle of the cable should be slave)
there are other configurations for this as well, just ask if you need help.
Ground yourself when your doing the work, and be careful.
and have your friend put the cover on his case next time so this dont happen again