what are you using to read the card. A card reader or through your phone. If it is through your phone you may need a driver for it.
I have a vista, xp, os x, and linux boxes and there are certain things I need drivers for on just certain boxes but they work fine on others.
it maybe the format of the card itself as well. Reformat it on the XP box with FAT32 and not the phone and see if the Vista box will read it.
just to add I literally hate Vista it pisses me off as much as ME did. We are supposed to roll it out to the boxes at work 1st quarter next year. What hell that is going to be.