Yes you can.
1) Go to Control Panel, select User Accounts.
2) Select Change the Way Users Log On or Off
3) Then uncheck the 'Use Welcome Screen' option
1) Click Start, Run and enter CONTROL USERPASSWORDS2
2) In the list of users, select the Account you want logged on automatically
3) Uncheck "Users must enter a username................"
4) Click Apply.
5) In the next dialog, enter the password for the account you selected in Step 2, if any.
6) Ok your way out.