Home Theater Setup- Overall help needed!

[Silverwing]

I've tried to save up and buy things needed to improve my home theater setup. Below is a list of things that I'm currently using. Any help on what I should change or could be a much better help (or any input at all for that matter) would be appreciated. Thanks. This is what I am using:

2 Mythos One Speakers (Definitive)

The ProCinema 600 Speakers (4 Definitive speakers, one center speaker, and a sub with a built in amp)

Denon AVR-1507 Home Theater Receiver (no hdmi support)

50-inch Panasonic TH-50PZ700U 180p Plasma HDTV

Panasonic DMP-BD30 Blu-ray Player (came with tv is it better then a ps3 when watching movies?)

I also have a Playstation 3, but do not use it for blue-ray movies (is that a mistake?)

My recently purchased Mythos speakers are great and the deal I got for them was far too good to pass up. However they do over power my other speakers. Although I can still her the rear speakers pretty clear, it's the side speakers (LS, RS) that seem to do nothing noticabley.

My receiver is where I think my problem is, well more of an issue then a problem. I do not have HDMI inputs in my receiver thus I'm using optical for all my sound. Also my Blu-ray player isnt the best (not giving Dolby TrueHD).

Again any help for what I should upgrade or simple things that I already own and can change like auido settings or what not would be great. And when/if making suggestions for upgrading please make them somewhat reasonable in price Thanks again!