Check out a few web sites.

www.homelogic.com

http://www.alienware.com/Product_pages/media_center_all.aspx?cs=2

www.nexusaudiosystems.com

If you are trying to do this yourself, the sonos music system might be right for you.

If you don't really NEED a plasma, JVC's DiLA TV's are very good.

Sat VS Cable box, in my area cable is winning as far as HD channels go, the rest is the same. You should check out channel line up in your area.

Sirus VS XM, both work well, but each has some channels the other doesn't, really up to what you want to listen to.

Home theatre, stay away from cheap HTIB systems if you actually are interested in enjoying the system.

Your list is something an Integration company really should be called in to deal with. If you want things to be easy to use, and to make the right decisions on what equipment works best with each other, they would be able to put everything together. You do have to be willing to spend some money.