Try
> import wmi
> conn=wmi.WMI(None)
> res = conn.Win32_PerfFormattedData_PerfDisk_PhysicalDisk()
> print res[0]
If it doesn't work, try:
> import pythoncom
> pythoncom.CoInitialize()
> import wmi
> conn=wmi.WMI(None)
> res = conn.Win32_PerfFormattedData_PerfDisk_PhysicalDisk()
> print res[0]