since you are new to guns and plan on getting a carry license, I HIGHLY recommend that you take some sort of gun safety course so you can keep yourself safe as well as others.

As far as stopping power, I would get a .40 over a 9mm any day of the week. I mean, sure, a double tap to the head w/a 9mm will do the trick, but since you are new to guns, that isn't a very likely scenario. I prefer a .45 cal, but that's just me.

also, I've never bought into the Glock hype. I mean, sure, they are great guns, but there are other brands out there that are just as reliable such as HK, Springfield & Smith & Wesson. I read an artical on the Springfield XD where it went through the Glock torture test after it already had 15k rounds through it and had 0 malfunctions after the test. That being said, you might want to consider a gun that has more than a "trigger safty" for your first gun.