Switch users in one click / shortcut

Hello,

I should really post this to vista.customize, but there isn't such a
group so I post it here, answers for either xp or vista will do.

I have just created 2 users, one for my girlfriend and one for myself.
To switch from one to the other (leaving the first session open,
locked really), I need to click on the menu switch user, then click
'change user' on the next screen, then click on whichever user I want,
then type the password etc...

Not very fast, is there a way to automate this ? Ideally I'd like to
have an icon on user 1's desktop, called 'user 2' (and vice versa), a
click on the icon would go through all the process (and ideally enter
the password).

Is there a way to do this ?
Thanks
Antoine