I second this. It has been a few years since I've done any skiing, but I was reasonably impressed by Whitetail for a mid-atlantic resort. It's just about equidistant. Seven Springs is fine, too, but that would be much farther for you to get to from Philly.

To get to Whitetail from Philly you would take the Turnpike west, exit at Carlisle and take I-81 south. Your friend would take the Turnpike east, exit at Breezewood and take I-70 east. Directions from there as well as all the other info you need are on the web site http://www.skiwhitetail.com/

EDIT: Another one I forgot that's, well, still farther for you but closer to equidistant than Seven Springs is Blue Knob http://www.blueknob.com/ Just if you wanted another option to look at. It is the tallest skiable mountain in the state, but you may not find it worth driving farther for.