Aaron, read the first post.... he's trying to do just that.
My suggestion would be as follows: get the data of the card onto some other pc and plug your phone into the laptop. Let Vista format the card and see if it works okay now on the phone. Connect to the pc where you left the data, copy it back and then put your mp3's on the phone's card.
I think the same as you did: Vista has some problem reading the card, probably because of the way it's formatted. (Stupid Vista...