He is exactly right on all points. I got on here today to ask about powerline adapters myself.
I would not buy these for my house. The way wireless is now, it's super fast anyway. I have a Cisco E4200. If you have a good wireless adapter you'll be transfering faster than a powerline adapter will take you.
The powerline adapter signal will degrade based on the wireing in your house. There are two different adapter technologies. If you're searching for a "deal" on a set of powerline adapters, I suggest going to Howstuffworks.com and looking at it. You don't want to buy the old ones :P
The reason I'm interested in them is because I have a barn about 50-60 yards away from my house. I don't want to set up a bridge, I would rather "powerline it" straight across. (The barn is more like an apartment). I'm fairly certain it won't work. I don't want to explain the complications of our grid if I don't need to!
I want to have at my house:
CiscoE4200 (for wireless gaming/streaming moves/wireless printers) > Powerline Adapter
Barn: Powerline Adapter > Another E4200 to wirelessly stream movies/games from my house.
I'm going to buy some adapters today. If you can wait a week I'll get you an update and show you for sure your set up will work
Newegg.com - TRENDnet TEW-684UB Dual Band Wireless N Adapter IEEE 802.11a/b/g/n USB 2.0 Up to 450Mbps Wireless Data Rates 64/128-bit WEP, WPA/WPA2-RADIUS, WPA-PSK/WPA2-PSK, WPS
It has four eggs because a few DoAs gave it a one egg. 450MB/s is more than enough to stream.