Hi Julie
Just some more ways to get it out
Take a GOOD screw driver and place it on head ,on dead center of the screw and then strike the screw driver,this will drive the screw down just a bit,but you must hit it hard,BUT not to hard you don't want to break the base.
They make may tools to get them out, the one I use all the time on ALum.bike eng. looks like a hvy. punch that you put in driver bit,when hit the tool it that turns the screw just a bit and will free it.
ABout a 10.oo dollar item at the auto parts store.
IMPACT SCREWDRIVER SET WITH CASE
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=37530
Here are some other tools to get it out but a sharp blow should do it.
Here's a fast, easy solution to stripped screws.
Just insert one of these super-tough drivers into the screw head, give a couple of taps with a hammer, and twist free. Chrome vanadium blades are specially designed to bite into almost any stripped head.
Steel-butted drivers with unbreakable vinyl grips.
Includes one Phillips and one slotted driver.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=38037
Craftsman 3 pc. Screw-Out™ Damaged Screw Remover Set
http://www.sears.com/sr/javasr/product.do?pid=00952154000