If you go CD, there are quite a few record pools you can join and get all the newest stuff sent to you based on your musical preference. I say if you're just downloading MP3's on the bootleg tip, be careful, because you're turning a profit on stolen intellectual property. I just do it for fun here and there, and I use a computer setup. I use Atomix VirtualDJ, but I've also used OTS Turntables before. Both allow you to scratch and there's even hardware you can purchase:
http://www.virtualdj.com/products/hardware.html.(Ripped) MP3's are much more portable than carrying cases of CD's that might get lost, scratched, or whatever else. But bascially, whatever you can do with CD mixers, you can still do with a laptop/hardware setup.
