It's user based setting in the registry.

For stretch: HKU\[SID goes here or write to HKCU]\Control Panel\Desktop\WallpaperStyle: "2"
For centre: HKU\[SID goes here or write to HKCU]\Control Panel\Desktop\WallpaperStyle: "0"
_________________________
Mart

- Chuck Norris once sold ebay to ebay on ebay.