I went from a pretty nice 5.1 set up with Aperion speakers and an HSU research sub. I'm now using a pair of STRTs all by themselves. As of yet, I do not miss my surrounds. On a movie soundtrack that is too dynamic, I wish sometimes I could bump up the center channel but can't. Most the time I'd never know I didn't have a center. I don't have a lot of seating, so all my watching is pretty centered. I do notice that if I'm off center standing on the side of the room that everything still sounds great but the soundstage is messed up and not centered (obviously).
Do I notice not having a sub? On non-action movies, regular TV, etc, not really. The STs dig deep enough for that kind of stuff. On films that do have big low end, yes I notice that I'm not getting that low but all and all it doesn't bother me. People have different tastes in sound. Personally, I find BIG low end kind of distracting. Even when I used my sub, I kept it fairly low key as I like a very smooth sound from top to bottom.
Someday I plan on hooking my sub back up but for now, I like what I'm hearing and love the simple, clean look of just having a pair of speakers vs cramming 5 speakers and a sub along with everything else.
You commented that you are new to audio. If you can swing getting a 2.1 or 3.0 set up to start with, go for it. But if you want to take it in baby steps, maybe just try 2.0. It's kinda fun taking things in steps to see the improvement. If you've never had good gear and never heard Salk speakers, you are in for a treat no matter what route you go.
What are you using for a movie source? Bluray? DVD? If you don't have a decent source, you may want to consider something like the Oppo 983 bluray player. It's a bargain at $500. Absolutely stunning for bluray and DVD and a great audio player as well that supports every format under the sun.
Good luck figuring it all out. That is the fun and agony of it all.