This is my first post, and I registered to reply to this particular subject, since I have experience in the area.
I have been DJing since 93, and I have gone through various laptops. In doing so, I have interacted with many DJs. Most clubs have Serato installed, and the most common setups I've seen use either Serato or Traktor. For both of these programs, the Mac is the way to go.
Here is why. Laptops running Windows run fine, as long as you know how to tweak and maintain it. A lot of DJs really don't know much about Windows, and when they start using the laptop for everything else, they complain that the DJ software glitches or runs slow. I had a Dell, and it served its purpose. I never used it for anything else and it worked fine. But I was constantly running various tweaks on it. I switched to a Mac about 4 years ago, installed Serato without tweaking anything, and it ran like a dream. I also used the Macbook for other things (Ableton, ProTools, CS4) and performance was never affected.
I recently picked up a 15" MBP i7 with the antiglare display because Serato is now going to integrate with Ableton, so essentially both programs will have to run at the same time, so I needed a little more power under the hood. As for my trusty 2006 White Macbook, it still runs like it did the first day I got it.
Bottom line....get the Mac, it'll mean less headaches later.
