is this your receiver ?
http://tinyurl.com/25frmvi'd keep that.
get a new source (oppo !!)
new cables
new speakers
speaker placement, as Chris suggested is crucial. Even w/what you are running you can make a huge improvement. Go w/the basic triangle approach.
think of your listening position. how far away from the speakers are you (in a straight line).
now space them out an equal distance (or a little less) so you are making a triangle w/equal distance from your head to each speaker, and them from each other.
pull the speakers out a solid foot from the rear wall, and equal distance from the side walls.
play some white noise. you can generate some w/software and burn a disc.
a dead radio station w/static noise will also work.
you will want to listen to pink or white noise to "dial in" the speakers. the goal is to have the static sound like its a "ball of noise" that is hovering in mid air between the speakers. Ideally, you will not be able to perceive the sound emanating from the speakers themselves.
start w/the speakers pointing dead ahead. have someone (its easier w/two people, one listening and the other tweaking) move the speakers in towards your head (toed in) ...just like an inch or so at a time until you get that "ball affect".
You might find that the speakers end up pointing to your shoulders while you are seated in the "sweet spot" instead of the straight ahead stance of where you started.
or...maybe not. depends on the speakers and the room, and how they play together.
Once you get that white noise dialed in as best you can (you may find it doesn't work at all due to limitations of the speakers performance..and if that is the case, get new speakers) then you can put on some music that you are very familiar with. Start with studio stuff (real releases and not AUD taped) and see what you think.
Hopefully, you will experience good imaging. Meaning that the music sort of floats in air, comes from "nothing" instead of the speakers. You'll hear voices, drums etc, coming from dead nuts between the speakers and not from the sides. Other sounds may come from way outside the speakers, or even seem to come from behind.
In a perfect setup, the music is completely holographic and is all around you...and you absolutely can't tell that the speakers are even "on" as you can't sense them as the source of sound.
Thats what we strive for any way.
the Stereophile test CD #2 is excellent for seeing how things are working, and also has white/pink noise tracks.