Hi there Gille,
This will work only if you have logged into the machine before.
When you get to the Welcome Screen (the sign in screen), press
CTRL+ALT+Delete twice, and you will get a Logon prompt. Type in your user
name in the user name field (remember that usernames are case sensitive), and
then your password into the password field. (If you never set a password,
just leave the field blank)
Then click OK to log in.
When you get into the machine, follow the link below to turn the Welcome
Screen off, then reboot the PC, log in like we just did above, then follow
the same link to turn the Welcome Screen back on.
http://www.microsoft.com/resources/.../en-us/ua_logon_at_welcome_page.mspx?mfr=true
Hope this Helps!
Best Regards,
~Will