BleepingComputer.com: Choose logon username without mouse?

I'm working on a Dell tower for a friend. It's a model that has only USB ports. I am unable to get past the username-selection screen because none of my USB mice (I have a dozen!) work.

Is there a keyboard command which will let me manually select a user (and then proceed to the desktop where, presumably, the machine will do a new-hardware scan and load drivers)?

To change the selection, use the TAB key.
And to proceed with a command (like OK), hit ENTER.

This post has been edited by ReviverSoft: 18 December 2009 - 05:44 PM