I assume you are working on Windows-7 and then its much easy to transfer the User profile. Just click on Start button and then type in search box Windows Easy Tranfer and click on it or you can run it as an admin.
Now click on
Now select the third option as you have to take it along with you.
Now select the second option after this Windows will scan for the files of all users on this PC and then you can copy them in your USB or external HDD.
Note You can use this method for transferring files form Windows Vista to Windows-7 too because this feature also available there.
If you want to transfer User Profile from XP to Windows-7/Vista then download Easy Transfer.
For Windows XP you can download this guide.