On Error Resume Next

'Priority Class Value
'    Low - 64
'    Below Normal - 16384
'    Normal - 32
'    Above_Normal - 32768
'    High - 256
'    Real_Time - 128

Const High = 256
strComputer = "."
Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\cimv2")

Set colProcesses = objWMIService.ExecQuery _
    ("Select * from Win32_Process Where Name = 'Explorer.exe'")
For Each objProcess in colProcesses
    objProcess.SetPriority(High) 
Next