What speakers to get for a small bedroom.

I currently just use the stock speakers on my vizio 37 inch tv (http://www.walmart.com/ip/Vizio-E370VL/13904833). It's okay but I would like to improve. I have a small to medium size bedroom and it is a bit cramped (Full Sized Bed in Left corner, a two person couch to the right of that, a computer desk in front of my bed, and my tv set in the front of my room in the wall space between my closet and door). The TV sits on a 3 shelf glass stand (http://www.walmart.com/ip/Accsense-W...Glass/10752189). The top shelf holds my tv, the second shelf holds my PS3 (Hooked up via HDMI), and the third is currently empty. I have been using this set up for over a year now and can tell that I'm missing something when I am watch a Blu-Ray movie or playing a game. I would appreciate any suggestions. I'm in no way an audiophile, but I do know the difference between good sound and mediocre sound.

I'd like to keep it below 400 if possible.

If a receiver won't take up a lot of room or over complicate it, sure. I could go either way though.

Thank you for all of the reply's. I have been considering a 5.1 system, but considering my room size and the cramped nature of it, how would that work out? And is installation going to be difficult? We are moving next year and my dad has said I can put a surround system in my room of the new house so I was just going to wait till then for a 5.1. Right now I am more looking for something to hold me over till then.