strComputer = "."
Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\cimv2")
Set colItems = objWMIService.ExecQuery("Select * from Win32_PerfFormattedData_PerfOS_Memory",,48)
GB = 1024 *1024 * 1024
For Each objItem in colItems
    Wscript.Echo "Available GB: " & Round(objItem.AvailableBytes / GB,3)
    Wscript.Echo "CommitLimit GB: " & Round(objItem.CommitLimit / GB,3)
    Wscript.Echo "Committed GB: " & Round(objItem.CommittedBytes / GB,3)
Next