John
Why not just download Virtual DJ? The home edition is free, and if you are just looking for the basics, it would be perfect. The mapping system is fairly straightforward, so you can actually map the keys to start/stop, cue points, loop control, pitch control, etc.
You can also download a demo of Traktor Pro. But it shuts down every 30 minutes. The mapping is also less intuitive - but very powerful if you can learn it. I've put together solid sets using just my keyboard before.
They're both free... give both a shot before making up your mind.