USB Turntables

I just purchased a Numark USB Turntable from Amazon and am quite excited to convert all of my vinyl to MP3s. However, I have one question: with 2 of these turntables, am I able to play "dummy records" that play MP3s straight off of my computer? I would like to do some DJing, but I don't want to carry all of my vinyl around with me. Just 2 blank records which can play anything would be ideal. I've heard about this, but I don't have any details or knowledge.

Thanks for your help!

Yes, but you have to buy the setup and as far as I know, you'll just be using the normal line out on the tables and not the usb.

Serato is the most popular. It comes with two specially time coded vinyl records, the box that connects the two tables to the computer, and the software.

It's about $500 for this setup
http://www.serato.com/products/scratchlive/

I saw that numark table at the sharper image a few days ago. that'd be nice to have. is it any good?
It'd replace a sony model i have that i picked up at best buy a few years ago for $100 new. Its a base model.
Bryan

If you're just playing vinyl, you're ok...if you want to scratch and/or mix/beat match....I'd skip it. It's belt drive...Look for a used pair of technics 1200's or the harder to find Numark TTX's...the TTX's have only been out for a few years where as the 1200's have been out since the dawn of time...

Direct drive is superior to belt any day of the week...