Google TV is TV over the web, still need a browser. No and yes to building a htpc, You can get dvd players, and these stand alone boxes that will stream netflix movies as well as other content from the web. It all depends what you intend to use / or how you intend to use all the steraming apps.
For my money I've got the PC plugged into the HDTV with a remote KB and mouse, and a netflix subscription.
Actually, I believe you will only need one box or the other or a newer DVD player.
These boxes hook to your internet connection and stream the media to your tv as you are watching.
If you want to see it go to Google.com/tv or do a free month of netfilx.
There's money to be made and everyones jumping on the wagon. Be careful as some are sure to fall off and be left in the dust.
I believe any of the streaming sites will connect with your PC as well as a set top box.
Thanks again. We had Direct TV and their PVR along with Netflix and Roku. We cut off Direct TV and really don't miss it much. I currently have just Netflix for DVDs and Roku for streaming and love it. I guess Google TV will just expand that.