Need help discovering disk-size

I know windows has a way of discovering disk-size of a share over a network, so it has to be accessible somehow to other programs, right? Does anyone know how I might go about calling this information? I'm in charge of designing a short C++ prog that reports the status of 14 servers in the mornings including space used/space available. I obviously can't pull a dir /s and use the information at the end because having it list our directory entire structure would take forever(and the load would be bad). Is there some way to get this information? Any dos commands even?

You could try the API function GetDiskFreeSpaceEx()