Noob Here: Did I make the right choice?

You will get a couple different oppinions, but mine is you made a good choice.

I find it's better to have nice quality L/R's and a sub, than lower quality 5.1. Later, when you get more money and feel an upgrade is necessary, you can add in the center and surrounds. I'm a fan of 2.1 and 5.1/7.1, but don't feel 3.1 is worth it.

So you would say that a 3.1 system is not better then a 2.1 for movies?

Correct. You will even see some people running 4.1/6.1 using a phantom center, i.e. no center, just the L/R's

That's up to you. I don't feel it is, but if you do it, you may love 3.1 and think I'm an Id10t for not liking it.

If people will be sitting to the left and right, a center speaker will help keep the dialog in the middle. This is especially true if any of the seating positions are substantially closer to one of the L or R speakers, since the person in that seat will hear all the dialog coming from the the speaker they are closest to. I'm not really sure why, but this seems to matter more for some speakers than for others. I suggest you wait until you have the system setup and then try sitting in each of the positions you care about. Some tweaking of the speaker position or toe-in, and the seating positions may help. But you might find that you just need a center.

Another issue that I noticed as I recently sold my 5.1 system and am temporarily running 2.1 until I get a new 5.1 system, is that the dialog sounds "doubled" when sitting off center. I'm pretty sure it is the sound from both speakers arriving at slightly different times. But it's noticeable. Calling it "doubled" probably makes it sound a lot worse than it really is -- it is just a minor effect and the dialog is still clear and easy to understand. But if you have to listen at low volume level, I think that adding a good center could improve clarity for off-center listening positions. (Adding a "bad" / low quality center could also make it worse, however.)

I'd still probably buy a sub before I bought a center, though.

-Max

Looks like plenty of room to me.
I think it will be well worth the "trouble" to add surround speakers.
It would be a hard choice but if I had to choose between having a center channel or surround speakers I would choose the surrounds.