If the DirectTV HD Receiver will be your only video source, why don't you connect it directly to the display? Or even if it isn't the only video source you still could if the display has multi video inputs.

So far as speakers go, I think you might want to buy a complete surround speaker set. Totem is one company that makes nice sounding reasonably prices speaker sets.

Six Stirling LS3/5A V2 speakers plus a sub would be really nice, but it would cost more.