If you want to Make XP Logon Screen Look Like Vista you need to follow this procedure.
First you need to download logonstudio from here and install.
Stardock LogonStudio allows Windows XP users to edit, change, and apply new logon screens. LogonStudio comes built with a visual editor to make it easy to create your own logons which can then be uploaded to websites to be used by others users.
Now you need to download vista ultimatelogon screen from here
Once you open logonstudio you need to click on load and select your downloaded vista ultimate logon now click on apply and ok
Note that this will not work if you are logging into a domain, or if you use the classic style logon with Ctrl+Alt+Del.