Glenn,
If I run your script, it says
 Code:
Not Enabled.

While my Quick Launch Toolbar is enabled.
I presume the script should be something like:
$TaskBar = ReadValue('HKEY_USERS\'+@SID+'\Software\Microsoft\Windows\CurrentVersion\Explorer\Streams\Desktop','TaskbarWinXP')

; look only at bit 0
$TBFlag = Val('&' + SubSTR($Taskbar,18,1)) & 1
; determine if it is on or off
If $TBFlag
    'Enabled!' ?
Else
    'Not Enabled.' ?
EndIf