Cant log in.

Did you put her out or kick her out with your boot? Hope you didn't turn on File Vault security setting.  Your fuc..d cause File Vault is super secure and you got to be asian to crack this thing.
If you don't got File Vault on there might be some hope for you dude.  When you turn your computer on a login screen will prompt you for password.  Type in some bullsh.t random letters and hit enter.  Now do this again and on your last attempt a screen will give you a chance to reset the password.  Type in your master password to override the login password and then change the login password to something you can remember.
If the above don't work cause your too drunk or high to remember the master password or you never set up a master password, then go get your Mac install disc and load it up into the computer.  Now press and hold the power button to turn off the computer and wait a few seconds after shutting the thing off.  Now turn the thing on and hold down on the letter C.  The disc should start installing.  Choose installer-->reset password.  Select your hard drive on the screen, then click on your user name.  Now type you a new password in both boxes and click on the save button.  Close out of the window, click on the installer tab, and then restart.

http://www.macobserver.com/tip/2003/06/16.1.shtml