http://www.h-online.com/open/news/item/USB-driver-bug-exposed-as-Linux-plug-pwn-1203617.html
http://www.h-online.com/security/news/item/GNOME-screen-lock-ineffective-in-openSUSE-Linux-Update-928794.html

Two choices [GNOME, Fedora 14]:

1 - use the gnome-screensaver
2 - use the "switch user" function [gnome menu -> log out -> switch user]

So the question is: which one is the safer method to lock the screen, if a user leaves the pc?

Is it true, that using the [2] method is safer?

Why do i think this? - The gnome-screensaver is just a "process", it could be killed. But if you use the log out/switch user function, it's "something else". Using the "switch user" function, could there be a problem like with the gnome-screensaver? Could someone "kill a process" and presto...the lock is removed?
Could the GDM [??] "login windows process" [e.g.: http://www.labtestproject.com/files/screenshot/fedora12/042_fedora12_kde_login.png] get killed and the "lock" gets owned?
Thank you for any opinion!

p.s.: if the [2] method is safer, then how can i put an icon on the GNOME panel, to launch the "switch user" action by 1 click?