Well based on the numbers mentioned it would be more like 10x. I get somewhere in the 20-40Mbit/sec range and have seen 50Mbit at some point (I said Mbyte/sec before).

I don't have cable at both ends either so no use to me. I'm considering looking at Wifi N. From the living room I easily get 12-14 MByte/sec from my router on 802.11n 5GHz to my laptop. However I feel the problem is more MythTV's lack of buffering than anything...