Filling out 3.1 on a budget

[xander]

Greetings All,

For starters, I apologize for even starting this thread, but after a couple days of reading through the threads here, I find myself completely overwhelmed with information and locked up on any direction to go in. I would hope my long time history here (feel free to check my thread starting history) buys me a little leeway. I adore this site and consider this the finest resource on the net, so I am biting the bullet and asking for help. I finally through a set of events in the past couple months that would leave you shaking your head at my poor decision making abilities jumped into getting some sound to finally go with my HD video set up. Rather than bore you with that tale, here's the pertinent things you need to know to potentially assist.

I am running with a Sony STR-DH520 Receiver, hooked up to a Sony SA-W2500 Sub, and (wait for it), a Vizio soundbar. Although it was a huge leap up from my tv speakers, obviously it just makes me want more. So, I want to replace the soundbar with a center and left/right. Everything is new, so jettisoning the receiver/sub is not an option. The particulars:

-Small room, 13' by 15' with open doors to the kitchen/hall
-Rears are not an option at this time due to a number of reasons
-VERY minimal space, so I would be looking at small speakers, probably to place on the tv stand.
-Similar minimal budget. Probably $350 would be my cap.

Questions:

-Am I going to see a significant sound improvement? (the sound bar is loud and.....well that's it. It's "settings" (truvolume, fake surround, etc.) drive me nuts.
-If this is a good idea at all, suggestions on what to buy would be AMAZING.

I'm sorry for the epic ignorance on my part, and thank you for your help. I trust this community a ton to point me in the right direction, even if that is to just keep the bar.

Here's a pic of the space I'm working with. (I'm about as talented a photographer as I am with audio)