how to determine the os of a remote pc

i am working on a automated remote backup program make copies of users desktops. I need a way of telling (remotely) if the PC has XP or Windows 7 installed.

All the PC's are in active directory.

I am using VB6.

Is there a way to remotely tell which OS is installed?

Thanks!
R

Tried WMI yet?

No. Im googleing my fingers off to see what that is.