Well, the SP101 is a five-shot gun, which might make IDPA difficult, but will certainly do the job. You'll just have to reload... quite a bit. IDPA has lower round counts per stage that USPSA and other disciplines, but some stages can still run into 12-18 shots at minimum. That being said, if that's the gun you have, and you have a good holster and a few speedloaders, head on out and shoot a match with it. If you've never done any "action-type" shooting against the clock, you're not going to win the match anyway, no matter what kind of gear you have. The main thing you need to know you probably already know: how to manipulate the gun (in/out of the holster, load, unload) in a safe manner. I don't know what club you're thinking about going to, but wherever it is should be pretty "first-timer" friendly. Being the "new guy", you're probably going to be watched extra closely: don't be insulted, remember, the folks running the match have NO idea as to your skill level, safety, or anything. If they teach a little "below your level", don't take it personally, just keep in mind they don't really know where to start with you, so it's just quicker to start "at the bottom". Trust me, if you shoot a couple of stages and show yourself as safe and competent, you'll quickly gain respect and not be smothered.
As for the shooting itself, my biggest hint is go slow, be deliberate, make your hits (most targets require two hits on paper, with the number of shots fired unlimited), and spend the first match or two just having fun, being safe and hitting the targets. Trust me, the speed will come, the faster you try to go, the slower you'll probably end up going. Listen very closely to the "walk-through" description and instructions before each stage. The RO will ask if you have any questions... if you do, ASK THEM! Nobody looks dumb asking a question... lots of folks look dumb doing something dumb because they didn't know what to do. If something appears unsafe, that probably means either a. it is unsafe... the folks that put stages together are good, but not infallible, sometimes stages happen that create serious problems; or b. you don't fully understand what you're supposed to do, and you think what the instructions are telling you to do is unsafe. Either way, you need to get that fixed, and the RO will be happy to fix it. IMHO, the "goal" for the first match would be to finish with no "procedural errors" (time penalties for not properly using cover, shooting targets out of order, and other infractions based on the instructions for a particular stage). The good news about that goal is that it's pretty easy to accomplish: just pay attention to what the ROs tell you do and go do it; stay focused and you'll be fine.
IDPA is an excellent way to improve the basic skills that will help you defend yourself with a handgun. It's not a replacement for good training, but will certainly complement it. It's also tons of fun, and a great way to practice running a gun under stress. It's nowhere near the stress of an actual armed encounter, but a heckuva lot safer. If you go shoot a match or two and decide it's something you want to keep doing (most folks get hooked), you probably will want to move to a 6-shot revolver or a semiauto. Most factory handguns can be fully competitive in one or more of IDPA's divisions. Matches are usually very social outings as well, and just about every competitive shooter I've ever shot with has been a great person. If you ask, most shooters will be glad to let you try his/her gun for a few rounds after the match is over, so it's a great way to try out different guns to see if you'd like them.
Well, I've talked too much already, so I'll leave it at that. Go check out the IDPA website and familiarize yourself with the rules and range commands (don't sweat memorizing it or anything, the ROs help you through). Get out and shoot a match, tell us how it goes!
DanO