Code:
If NOT @LOGONMODE
	Break On
Else
	Break Off
EndIf
Dim $RC
$RC = SetOption("Explicit", "On")
$RC = SetOption("NoMacrosInStrings", "On")
$RC = SetOption("NoVarsInStrings", "On")
$RC = SetOption("WrapAtEOL", "On")

Dim $Entry, $Value
$Value = "YouKnowWhatValueItShouldBe"
; Is this the value?
; $Value = "e001000000000000c4ffffff00000b0000000100020000000000000000000300000002000200000000000000"
$Entry = ReadValue("HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones\Pacific Standard Time","TZI")
If NOT $Value = $Entry AND @DOS = "5.1"
	;Do stuff, install update
EndIf