Set WSHNetwork = CreateObject("WScript.Network")
WSHNetwork.SetDefaultPrinter "HP LaserJet 6L"

Set oShell = CreateObject("WScript.Shell")
strValue = "HKCU\Software\Microsoft\Windows NT\CurrentVersion\Windows\Device"
strPrinter = oShell.RegRead(strValue)
strPrinter = Split(strPrinter, ",")(0)
WScript.Echo strPrinter