The intuitive "MoveFile" API function works:

DECLARE INTEGER MoveFile IN WIN32API STRING source, STRING destination
? MoveFile ("c:\OldDir", 'd:\NewDir')
Where success returns 1, failure 0. Note: For directories the trailing "\" appears to be optional.

Or you can use the Windows Script Host (if installed)

oWSH = CREATEOBJECT("Scripting.FileSystemObject")
oWFH.MoveFolder("C:\OldDir", "C:\NewDir")

Rick