"lock screen"

wiggle your mouse.

hit the button beside the password box.

log in.



hope you have either kernel 2.6 or a lot of RAM....:D

but then how do you switch between them real fast?

and I have only 512 MB :)

That's a different package. Requires configuring. I've never done it that way. I'd think that a lot of switching would not be too good for the monitor, as it seems to be switching between modes every time the session is switched. Maybe I'm wrong.