since you want to go digital...
1. traktor for a more traditional dj feel. best with a dj mixer-ish controller like the vestax vcm 100 or the xponent. or cheaper, bcd2000 or bcd3000 (a lot flimsier tho). bpm detection plus the almighty sync button which is a great timesaver. you cn get really creative on your mixes with traktor... google search "ean golden" to get a taste of what you can do with traktor.
or you could go with...
2. ableton live. purists would probly say this isnt "dj-ing" strictly but whatever. eliminates the element of beatmatching because tempos are aligned automatically with a little preparation, so you can focus more on a really creative and crazy live mix. layer loops, pile on all sorts of effects, do live remashing, all on the fly. i <3 live. use a midi controller. uc33 offers a lot of control and its cheap, so good to begin with. google "moldover" or "bassnectar" to see the power of ableton live.
if you want a mix between classic analog mixing and digital file manipulation- get any of the timecoded systems: Serato scratch, stanton final scratch, or m-audio torq. torq is the cheapest option, but the serious djs seem to tend to go with serato... people say you can put on more of a show if you actually have decks in front of you but thats a matter of opinion. of course, you'll need a decent dj mixer and 2 decks/cd players.
