Seems that one of the more recent options isn't included in the poll question. As it is an option I'm currently using I figure it can't hurt to mention it here.

I currently have a great home theater system with carefully chosen speakers and receiver along with a 52" plasma. Rather than build a custom PC to go with it I chose to use a wireless HD media streaming device instead. I have the Asus HD O!Play Air.

It connects to my wireless G network and is able to stream HD content, music, and pictures from any network drive.

This way I can spend my money on my gaming rig instead of a HTPC.