OK I figured this out. You can disable the Autoupdate task right from EPO via "General Options Policies". It's in the client GUI as well somewhere I think.
For the Full Scan for instance if you want to disable that it's registry time. Found the answer for this in another thread. Go to the following key in the registry.
The value of "bSchedEnabled" needs to be 0 and not 1 to disable the task called Full Scan. The CLSID is the same for XP/Vista/2008. Haven't checked 2000 or Windows 7 but guessing they are probably the same. So now need to deploy that registry change via group policy or batch file.