the serato has its own built in soundcard so does not need to use the one in the laptop.
in the ttm57 its built inside the mixer but if you just buy Scratch live on its own it comes built in the interface box.
details on sctrach live
www.rane.com
details on the TTM57
www.rane.com
I just got my TTM57 yesterday and its worth every penny (or cent if you're in the US)
