Need help setting up speakers

Good afternoon,

Equipment:
Samsung 40" LCD
Xbox 360 connected to TV via HDMI
Logitech Z5500
Computer

I want to hook everything up to my speakers and get best sound.

Currently the way I have it connected is like this.

I have my xbox plugged into my TV via HDMI, I have my sound on the tv disabled. I have a toslink cable plugged in from tv to Z5500. I have my PC connected to my speakers using the analog cables (I believe that's the correct term) My pc has SPDIF out and I heard it's way better to use that (currently the way I have it I hear some static on the center speaker no matter what preset I use).

I want to buy a bluray drive but I want to make sure I have the sound set up correctly before I make the purchase.

my z5500 have 2 optical inputs but they are not the same type (not sure how to explain)

How can I plug my pc into my speakers without having to disconnect the tv? Is there some sort of dual SPDIF connector?

I'm sorry if this post is confusing, but I'm just as confused typing it up lol..

If anyone has any suggestions please throw em out there.

Thanks in advance...

after researching this topic I have come to realize that I am not getting true 5.1 with my current setup (xbox > hdmi to tv> tv using toslink cable to speakers)

My question now is...

Is there some kind of receiver that has multiple SPDIF inputs that I can plug all my stuff into and then connect that one receiver to the speakers? If there is something like this will it provide true 5.1?

I have the same setup in my bedroom. What I did was got an ATI 4350 video card with a built in HDMI output. This delivers video and audio to my TV so that my toslink output from the TV will sopply 5.1 sourround sound to my Logitech speakers. I did add a Blue Ray to my HTPC and the 4350 does a great job of video delivery to my TV. You can get a 4350 for about $35. I bought the Asus with heatsink so I would not hear a fan