Given the hornet's nest I stirred up with my first post, it seems that a little info on how to get started in 3 gun might be in order.
First off, don't worry too much about the gear. Spending a ton of money to get into the game, only to discover a few months later that you want to head in another direction is a surefire way to alienate your significant other. Trust me, you don't want to do this, as you'll need their support. Go shoot what you have, even if it's not ideal; you'll learn much more about what works and what doesn't by shooting in a match than you ever will by reading blogs like this.
See all those guys with the fancy jerseys that look like a Brownells catalog threw up on them?
They all started in the same place you did, and they have long memories, so don't sweat it. So long as you're a safe, competent gun handler you'll be made very welcome.
The sport is divided according to equipment. Let's take each of the divisions in turn and look at what you need to compete, bearing in mind the paragraph above. I'll assume your range bag has eye and ear protection in it, a cleaning kit, ammo and spare mags.
This is by far the most popular division and the barriers to entry are perhaps lower than any other. You'll need a semi-auto rifle with detachable magazines, a semi auto shotgun that will preferably hold eight rounds in the magazine and a semi auto handgun of 9mm caliber or greater. A secure holster and means of carrying spare ammo complete the rig. And that's it.
You don't need anything fancy (but trust me, once you're bitten by the bug, it can get expensive). A vanilla AR15 with a low power variable scope is a good place to start, though if you have any of the current piston-driven carbines such as a SCAR or ACR you're in good shape as well. I've shot with guys who've run Mini 14s, so if you have one, bring it. Add an extended mag tube to the Remington 1100 lurking in the back of the safe and you have the shotgun component covered, though if you'd rather run your trusty pump gun until you figure out which semi you'd prefer, that's cool too.
Most guys run 9 mm handguns as the capacity advantage over a .40 or .45 is significant, but whatever you choose, your holster is as important as the piece it contains. Bump a loaded pistol out of your holster in the middle of a stage and you'll be going home early, so invest in something that holds it securely. I have a fondness for Bladetech gear as they're located in my neck of the woods and offer great value, but there are plenty of others. If, after shooting a match you decide that you'd like to progress a little further, then the first thing you're going to want to buy are shotgun shell caddies, as loading from a pocket or bandolier sucks.
Here's my list of guns suitable for getting started in Tac Optics division. It's by no means exhaustive and I welcome additions and comments from current competitors, though if you recommend the first rig a newbie picks up consists of a JP CTR-02 with Leupy Mk8, Salient Benelli and Benny Hill tuned STI, prepare for hilarity.
Rifle: Pretty much any flat top AR15 - your choices are many. Doesn't matter if it's a carbine or rifle, just shoot the damned thing.
Optics: Too much for one post, fill your boots with knowledge here.
Shotgun: FNH SLP, Mossberg 930, Benelli M1 or M2, Winchester SX2 or 3, Remington Versamax
Handgun: Glock 17, 34, Springfield XD, XDm, S&W M&P, STI Edge, Para Ordnance p18, CZ SP01
Any of the above combos keep you in the sport for several years before you get anywhere near your performance ceiling. Buy used wherever possible, but not from a 3-gunner, as most people never fire enough rounds to wear out a gun. Three-gunners do.
Whatever equipment you select, remember that the item that has by far the biggest effect on your scores, is the one behind the trigger. Rather than go further into the library of tips and tactics, I found a complete guide to what you'll need, courtesy of my friends over at 3 Gun Nation.
Questions or comments?