[barrkel]

On Windows, Autoruns from SysInternals (http://technet.microsoft.com/en-us/sysinternals/bb963902.asp...) works fairly well for finding out about these things that happen automatically, and disabling them, as easy as unchecking a checkbox. There's at two categories relevant to googleupdate: CurrentVersion\Run, and Task Scheduler.

[barrkel]

Too late to edit: there's a third one, in Services, on my machine gupdate1ca54[more hex digits] - it also links to googleupdate.exe.