What do you mean by 'not recognized'? Any time you attach a USB device to a Windows computer, it will ask for a driver unless one is already installed. Do you mean it doesn't ask or it can't find the driver? With Device Manager open does the listing you are seeing disappear when you unplug the GPS?
The Vista 64 driver is available on Windows Update. Sometimes the easiest way to get it is leave the GPS plugged in and go to the update site.
Terry