Does turntable mixing define a DJ or can a computer DJ rock the house just as hard?  Personally, I think it is all preference.  They are both good skills to have, as computer DJs can often produce music that turntable DJs just cannot produce.  With that said, I don't think Turtable mixing defines the DJ.

Does scratching make the DJ? 

I’m an aspiring controllerist, or digital disk jockey.  I’ve only really been messing around with production programs for 3 or 4 months, but already I’ve noticed a trend.  Apparently you aren’t a DJ if you don’t have outdated vinyl albums and you scratch (at least, according to many).  I’ve heard this from “oldschool” DJs (most of whom nobody’s ever heard of) and crowds alike.  I was promoting for a festival in downtown San Diego last Friday and I had a couple tell me Felix Da Housecat was a terrible DJ because he didn’t scratch.  I don’t get into arguments with people like that because you can’t change their minds, so I laughed and moved onto the next bystandard.  As I stood outside of the club listening to FDHC’s set and passing out flyers I thought to myself, “who the hell needs scratching?”

Personally, I think it’s just jealousy.  DJ’s spent so long mastering the scratching technique on technology that was obviously on its way out the door (turntables).  Talking trash about controllerists (DJs who use midi controllers to modify the audio properties of the files they are playing) is a way of validating their own hard work.  Controllerism is the way of the future.  I’m not saying that scratching will ever be a useless skill, but it’s not necessary.  Joel Zimmerman (AKA Deadmau5) plays sets all the time, without scratching (or using vinyl as far as I can tell) and he BRINGS THE HOUSE DOWN.  Tons of DJs out there do the exact same thing.  I suppose it all depends on style, practice, and personal preference.

So, in my quest to become a somewhat successful DJ, I think I’ll keep buying midi controllers and spend time learning scratching when I’m bored of everything else.

Well, the PC/MAC industry has ensured that many households in America, and it's a good way to start learning about music. Why computers first? Let's look at the price differences.  How much money do you NEED to spend to perform with a computer or vinyl?

Assuming you don't already have a computer:

Laptop - $1000

External Sound Card - $200

USB Mixer - $300

Ableton Live (All in one Software) - $500

Music - $.99 per song (unless it's free)

Samples - Free, or $99 for the Deadmau5 x-pack (higher quality)

Total: $2000 + Samples/Music

Total if you already own a laptop: $1000 + Samples/Music

So, vinyl seems cheaper to start.

True but what can you do with vinyl?  Well, you can mix other peoples music.  You can apply a few effects with the filters on the mixer, and scratch.  You can mix between to songs.

With a computer, you only have to spend more if you do not have a laptop.  Otherwise you spend the same amount.  What can I do with this laptop?  I can perform other peoples music, mixing it together with Ableton and with your USB mixer.  I can remix music.  Most importantly I can create my own music.  Can I scratch?  No, but I can replicate the sound pretty easily.  I can also modify the sound in more unique ways for the performance itself.  There's much more freedom in it.  I can easily create my own beats, mix my own loops, even create a completely new song.

It seems the benefits from spending a little more money (MAYBE) are obvious.  I'm not saying mixing vinyl is a bad skill to have, eventually I'd like to learn how to scratch well.  The point is, vinyl no longer determines the DJ.  It's called electronic music, and computers are the most common electronic device around.  How long could the electronic scene have gone without digital controllerists?  Not long at all.  I'm happy it did, and I'm also happy there are vinyl DJs.  They both have their benefits, and they expand the musical community as a whole.  In my opinion, that's a good thing.