unfortunately there are no easy answers. in addition to the questions from PeruvianSkies (imo you should seriously consider question # 5), what is it about your system that your are unhappy with?

i think for all those speakers, your room is very small. if your receiver can accommodate it, run only the surrounds and sub in stereo mode and see how it sounds. expand your horizons, in other words, get out and listen to different systems and components. this does not include demos at Best Buy, Circuit City and the like, the chains are strictly off limits. look for a local audio society/club and listen to the members' systems, as well as any local members of this forum who would be willing to offer you and audition of their system.

thats just for starters, it will take time and effort to educate yourself as to what a "high-end" system is, and to how close you can get to it within your means. i didnt come up with the saying, but its true, "we all get the sound we deserve".