Can I start with just a center, 2 sides, and sub woofer connected to a 5.1 receiver, & add surrounds later?

Question

I have a small room and don't know if I want surrounds.

Answer 1

Absolutely.  The good thing about getting into home theater is that you can buy things one at a time so that you get what you want over time.  But that way you can get some pretty nice equipment.  It's better than trying to get everything all at once, having a fixed budget and getting some crappy stuff.

You're on your way with the center, fronts (sides) and sub.  In your receiver setup menu, you can actually tell it that you don't have rears.  What your receiver will then do is reroute the rear channel information to your fronts.  So what would come out of the rear left speaker if you had one will simply come out of the front left, and the same thing will happen of course for the right.  This way you do not lose anything that you would hear if you had all 5.1 speakers.  

Though your receiver will do this, it is much better to have the surround speakers so that ambient information will be coming from behind you.  But you can add those when you're ready.  Until then, enjoy!

Answer 2

Sure. The connected speakers will work fine without surrounds/rear speakers. You will occasionally miss something that should have been reproduced by the surrounds, but 5.1 tracks don't have that much information sent to the surrounds .... and what is sent is rarely that important. The centre channel carries most of the dialog.