You already know how to transform Windows Xp to Windows 7 and Make XP look like Windows 7. Incase you don’t want to mess with your Windows XP but want just Windows 7 style Logon then here Windows 7 Logon pack for Windows XP.
mjamil85 one of Deviantart user has developed Windows 7 Logon Pack v1.1 for Windows XP and Windows 2003 which will makeover your Windows XP Logon process and animation to Windows 7 Ultimate Logon.
Screenshot of Windows 7 Ultimate Logon Pack v1.1
Download Windows 7 Ultimate Logon Pack 1.1for Windows XP & Windows 2003