IDPA... what out! It's quite addicting.
IDPA is a totally different animal when it comes to shooting. I mean you draw and move and fire. You'll run from position to position and engage targets from standing, kneeling and on the ground (depending on scenarios).
If you think you can shoot from a bench - shooting will have a whole new meaning when you are under the clock and shooting on the move. You'll have to "relearn" how to shoot.
Just to give you a taste the next time your out and your regular range will allow it - step back 2 steps and then shoot your target while slowly walking those 2 steps. The up and down motion you'll have time.
It can be a bit scary at first but know that if you just
GO to one and just watch. Let everyone know it's your first time there. They'll welcome you with both arms and most often even match you up with some experienced shooters to walk you through.
DO read the getting started section
http://idpa.com/dps_info.asp
http://uspsa.com/dw/gettingstarted.html
The sections will talk about what equipment you'll need and what the safety procedures are. For both
FIRST go and watch. Bring your gear and gun(s) but be prepared to just watch. If the club can get you in that's great. Your first outing should be to focus on just getting familiar what the rules are and how to be safe. Your first time is totally to be safe and slow. You don't want to be DQ - disqualified. It does happen to experienced shooters too but it's embarrassing as heck.
Go with the attitude of having fun and learning. You'll get a kick out of it and you just may end up buying a whole lot of gear and ammo.