Don't try to reformat it or you'll never get your images back.
Try it in a card reader.
You can download some free software here that may help\you recover your images:
http://download.cnet.com/Zero-Assumption-Recov ery/3000-2248_4-10061981.html
I have used it successfully once before.
However, if the camera
and the PC say the card needs formatting, you may have lost everything.
If you then
do attempt to format the card (either in the camera or on PC) and it won't format, chances are the card has corrupted and that's fairly terminal.