I haven't looked into the .22 conversion, but I have heard good things about it. The only thing I fear is that while .22 shells are cheap, you do need to buy much better ones than the cheapest stuff or you'll still have all sorts of jamming difficulty. I'm cheap with my Ruger 1022 and thus while it's fun, it's still a bit frustrating to have to clear jams often. (But there are few rifles that are that cheap to shoot and enjoy *that* much aftermarket support...it's one awesomely cheap gun that every enthusiast should have around if for nothing else than helping introduce novices to the sport).
Mike definitely has the right idea if you want to get fairly serious about holes in paper with a pistol. You can get something *very* accurate for the same price as a Glock .40. But each has its place...I wouldn't be wanting to stop some dope-head coming through the window of my house with the .22. Okay, it would be better than nothing, but give me the .40 instead any day.
Oh, and if you want the most innaccurate pistol in the world, get a Kel-tec and your concealed carry permit. Thing will fit in your back pocket without drawing attention to itself if you want and still hold six bullets or so. It's more a "get off me" gun as outside of that kind of range you're probably not going to be able to hit much, but for folks who *have* to have tiny or they won't carry at all, it's a great option.
--Donnie, no, I'm not *usually* packing at an autocross, Barnes