i bought my computer from a friend and the password they gave me is incorrect

Are you logging in as Administrator or some other user? Chances are you can login as the Administrator and reset his password. You do this by clicking switch user then type Administrator in for the user name and no password, leave it blank. If this works, then go to the Control Panel and Click on User Accounts. Then select the top item by clicking the Green words "User Accounts". Now select the "Manage User Accounts" and Click continue on the Allow or Deny screen. Find his name in the list and click the Reset Password button. If the administrator has a password set then you will need to hack the computer which I can not help you with but there are others who will tell you how. hint "Kon-Boot".

If this is a hard disk password, I hope he is a good friend. Cos, if he isn't you won't be able to bypass it. Some hard disks have security passwords . So, if the laptop is stolen, it is no good. UK MP's are thieving scumbags. EU members are worse.

You can bypass the a Hard Disk Password (Drive Lock) if you have the administrator password to the BIOS. Usually when you drive lock a system they setup two passwords. One the user knows and one the administrator knows. If this is the case then the manufacture may have setup the drive locking for you and has the password. Call their tech support and they may be able to help.

If you don't want to reformat your system, I think you have to make a rest disk or use some tool to do all the job for you. Such as Windows Password RESet. Burn a boot CD with the program, and insert it into the problem computer and your password will be reset to "Blank". http://www.resetwindowspassword.com/