apple tv and roku - strong wireless?
The Roku HD has 802.11b/g WiFi. The Roku XD and XDS have 802.11b/g/n.
The Apple TV has 802.11a/b/g/n.

802.11n is the fastest network speed, and reaches the farthest. If the WiFi in your home is 802.11n, I strongly recommend choosing one of the players that supports that.