This should work, just put into notepad and rename to .adm
CATEGORY "Logon Settings"
KEYNAME "SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon"
...but test it first - I haven't used it in a while.
I've always got around this problem running a reg file before taking an image. Just google 'rasdisable'.
Alternatively, just run the reg file silently and it'll work automatically when the machine is next restarted.
Just run this on the computer