Stripped Computer Screw Removal

I figured it would be easy enough to just replace my hard drive by myself. I ended up stripping a screw trying to get mynold one out and then kept on messing with it trying to get it out. My brother stupidly tried to JB weld a screw driver to the screw to remove it but when he turned it the screw driver just came right up and left the JB weld on. I used a small engraver tool to remove most of the JB weld but I'm still left with very stripped screws. Any ideas as to how to delicately remove an extremely stripped screw from a computer?