hi, i need help with my logon screen 8O

there used to be a screen as im sure you know where u simply click ur username and then enter the passord if required.

recently when i boot up the comp it has changed to a winxp proffesional box..where i have to type the username and password.

how can i change it back.

plz e-mail me at johnhilton2004@hotmail.com

THANKS VERY MUCH. :D