Security: gnome-screensaver VS. switch user

Mon Feb 14 00:30:58 UTC 2011

People "usually" suspend their laptop, so that they can continue their work when they open the laptop. OK!

Two choices [GNOME]:  

1 - Menu -&gt; Shut Down -&gt; Suspend
in this case, the gnome-screensaver locks the PC. but the gnome-screensaver is just a "normal process", and it could be killed e.g.: 
http://securitytube.net/USB-Autorun-attacks-against-Linux-at-Shmoocon-2011-video.aspx
or using any method [video was just an example!!].

2 - Menu -&gt; Log out -&gt; Switch user -&gt; Suspend
in this case, the GDM [???] protects the user [i mean it locks the PC from other users]

Which one is more secure/safer?