All hope is not lost - below is a stepped instruction followed by another user to get the same device working in Vista.
"- make sure scanner not connected
- empty your windows/temp folder
- start up the mustek xp driver installtion til you're prompted with 'select language', exit out of this or switch screens, don't cancel
- go to windows/temp folder and copy the contents to a new folder
- physically connect the scanner to computer, when asked to look for driver, browse to the new folder
- will install and you can use this scanner with vista...."
A search on this site also returned this result.