I've had great success with Powerline adapters after trying wireless unsuccessfully (too inconsistent). Here's how I have my setup:
Upstairs - Linksys Powerline Adapter (PLK300) connected to my router. Besides the router, I also have my cable modem and HDHomerun QAM tuner located upstairs.
Downstairs(1) - Desktop PC that connected to the network using an older Linksys PLK200.
Downstairs (2) - Entertainment center connected to a Linksys PLS300 (4-port powerline adapter) that connects my HTPC, PS3, and NAS to the network.
For me, this setup works great. I get ~3.5 to 4.5 MB/s (as measured by Windows 7 file transfer) when moving files from my Desktop to HTPC or vice-versa. The HDHomerun easily streams 1080i content (Comcast) from upstairs to the HTPC. Although, I only have one of the QAM tuners connected, I haven't tried recording on both tuners simultaneously. I have recorded OK while playing online using the PS3 and downloading a file on the desktop.
I will admit that I have to be careful about saturating the network. I avoid copying a file between computers when I know the QAM tuner is streaming to the HTPC because I will get misses in the recording.
My house was built in 2001, so it's fairly current. However, powerline networking is really variable depending on construction. I might be kind of lucky because my adapters don't seem to care if that they're on different phases, if the clothes dryer is running, or anything. I literally just plugged them in and went. Obviously, I won't be streaming any uncompressed Blu-ray movies over it, but it works well for my needs.