If you go to Brian Renkens info-labview search engine at http://infolv.brianrenken.com/2000/02/09/22.shtm and enter "serial number" as the search parameter and select year 2000, you will find what you need I think.
You can find a vi set called windows api 1.0 written by Shaun Rumbell at http://www.users.globalnet.co.uk/~pseudo/ VI Library. Under this set of vi-s there's one called GetVolumeInformation.vi that will do what you want. Hope this helps
