If youre using serato DJ and controller, you can use Serato's record feature. If you are using Scratch Love, you can use another PC, with output from mixer to Line In on PC, and use Audacity to record..
i would agree with above...if ur using the controller set ur bit rate and output in serato itself..it records clean.i usually jus edit the begining and ending and add in my adlibs and stingers.