GAH! I stripped the head of one of the logic board screws!
I'm removing the logic board of my early '09 MBP 17' so I can remove the heatsink to replace the thermal grease with some better-applied high-quality stuff to see if I can improve heat transfer from the CPU etc. to the heatsink. This should improve thermals by a noticable amount from what I've read. I would be finding out for myself just how much this helps if I could just get this screw out! I was careful about it and everything; correct sized screw driver (from iFixit), enough downward pressure but not alot of turning torque. I got most of the other screws out without a hitch, and this one just started giving out without budging.
So! I need advice on removing said screw.
Edit: It seems I already have someone who can help me procure a replacement screw.