strComputer = "."
Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\cimv2")

Set colItems = objWMIService.ExecQuery _
   ("Select * from Win32_Environment Where Name = 'Xilinx'")

For Each objItem in colItems
   'Please change the path to your ISE 8.1 path'
   objItem.VariableValue = "C:\Xilinx81"
   objItem.Put_
Next

Set colItems = objWMIService.ExecQuery _
   ("Select * from Win32_Environment Where Name = 'Xilinx_EDK'")

For Each objItem in colItems
   'Please change the path to your EDK 8.1 path'
   objItem.VariableValue = "C:\EDK81"
   objItem.Put_
Next