I have run into this exact same problem before, and unfortunately nothing in Windows no matter the flavor (2000,XP,Vista, or Windows 7) will fix the problem. If you have a friend who has a mac try using the disk utility which will likely make your card usable again, although you will lose all the data on your memory card. Just make sure the card gets formatted with the FAT file system. It works best if you go to the root drive and format which will create the drive you would see on your phone.
