I'm running Virtual DJ 7 Pro with a Hercules RMX controller. The controller has built in sound cards so I can preview songs in my headphones without them being heard through the main mixer. I don't scratch, but I do beatmatch and crossfade my mixes. If I have to walk away from the gear, I can queue up a few songs in a list and have them automix but it's a little clunkier than mixing by hand. I will sometimes loop 8 bars of a song to aid in the crossfade.
I have several terabytes of music and karaoke that I carry on two external drives, and I keep some duplicates and some requests on the hard drives of my systems. The main system is a mini-tower that I've rack mounted. I used to carry it in a Gator rack case (as pictured) but now I have it in a smaller SKB case with a removable front and back. The case also contains a power conditioner, my lighting controller, a keyboard and a mouse. I always have more than one computer at any gig. If something freezes or has to reboot, the backup is plugged in and ready to play a song or two until I'm back up and running. If you can't afford two computers yet, then plug in an ipod with a go-to playlist as an emergency backup. NEVER have dead air. NEVER. I carry a couple monitors in a bag. One has a stand and is on the table, then I have two more that can mount on light stands or bars for karaoke or for video playback while DJing.
As far as sound, depending on the size of venue, I'll run a 6 channel Alesis board, a 12 channel Mackie board, a 16 channel Tascam board, or some combination thereof. I used to run everything through a pair of crown XTi amps and into a combination of Yamaha 15" 2-way mains and monitors (I have 6) and a pair of 18" EV subwoofers (2), but this year I added 4 powered JBL PRX 615 speakers and they're lighter and more powerful than the Yamahas, so I may dump all of the passive gear and get a pair of powered subs and 2 more of the PRX (they can lay sideways as mains or monitors) and call it a day.
In the pic below I'm running a pair of 15" mains forward with the 18" subs, three monitors, and a pair of 15" mains pointed backwards towards the beer garden. I think this was the last gig I did before buying the powered mains. I have a pair of senheiser wireless mics and a couple Shure SM58's for vocals, then a set of SM57's and a Beta 52 for micing the drums. I always carry a couple different direct boxes and a redbox for micing the bass, keyboards, or whatever direct if need be. The pic is from the board... I run a 50 foot 12 channel snake back to me.
As far as lights... I currently have 8 LED pars, 8 regular pars, 2 gobo mirror lights, 2 Chauvet Vue II LED pattern lights (ceiling and crowd), 1 Revo IV light (floor patterns), 2 PIX bars (3 foot wide LED mini projectors), a strobe, a laser, and some LED pin spots that work with a mirror ball that I only use at weddings. I've been using combinations of T-Bars and light stands (I think I have 5) and sometimes with or without an I-Truss that goes across the top. I'm planning on selling the I-Truss and replacing it with a big silver Goal post arch (triangle truss) I think it will have a bigger, more pro look than the normal stands.
It's always a growth process. It was only about 8 years ago that I started with a pair of speakers, a 6 channel powered mixer, and a CD+CDG player and worked my way up from there. the most important thing is to know your venues whether it's a small bar with a couple speakers and 2 LED lights, or a huge venue where you need to run extra speakers to a loft or another room (I've had to do both). You'll always find ways to get through any gig and then in your mind you'll know what additional gear you want for the next bigger gig. Plan how you get paid for every gig as 1/3rd to 1/2 going towards the business, once your expenses are paid for like gas or advertising, then the rest of that is set aside to save for gear, you'll grow your rig pretty quickly and be able to attack different venues.