Very well, here' my entire script, based on one I downloaded from this forum.

$hkcu = 'HKEY_CURRENT_USER'
$hkcus = 'HKEY_CURRENT_USER\SOFTWARE'
$screensavekey = $hkcu+"\Control Panel\Desktop"
$sysini = "%Windir%\System.ini"
$poleditkey = $hkcus+"\Microsoft\Windows\CurrentVersion\Policies\System"

if KeyExist( $poleditkey ) <> 0
$screensavetab = Readvalue($poleditkey,"NoDispScrSavPage")
if $screensavetab <> 1
WRITEVALUE($poleditkey,"NoDispScrSavPage","1","REG_DWORD")
endif
else
AddKey($poleditkey)
WRITEVALUE($poleditkey,"NoDispScrSavPage","1","REG_DWORD")
endif

; We have a key, and the tab is hidden. Now change other settings...
IF 600 <> Readvalue($screensavekey,"ScreenSaveTimeOut")
WRITEVALUE($screensavekey,"ScreenSaveTimeOut","600","REG_SZ")
ENDIF

; Turn screen saver on if it isn't already for non BDC London group members
IF 1 <> Readvalue($screensavekey,"ScreenSaveActive")
WRITEVALUE("HKEY_CURRENT_USER\Control Panel\Desktop","SCRNSAVE.EXE","logon.scr","REG_SZ")
WRITEVALUE($screensavekey,"ScreenSaveActive","1","REG_SZ")
ENDIF

; Password protect the screen saver
IF 1 <> Readvalue($screensavekey,"ScreenSaverIsSecure")
WRITEVALUE("HKEY_CURRENT_USER\Control Panel\Desktop","SCRNSAVE.EXE","logon.scr","REG_SZ")
WRITEVALUE($screensavekey,"ScreenSaverIsSecure","1","REG_SZ")
ENDIF