if you like a wide variety of boxing, there is some boxing on roku - on both the iTunes Podcast channel and nowhereTV, under "government," there's Armed Forces Boxing Championship. - on nowhereTV it's under government and then "the pentagon channel"
the pentagon channel is also available as a free standalone private channel
NowhereTV also has classic/greatest hits HBO boxing videos and ringside audio of some recent matches
for paid channels, wealthTV has some boxing but i'm not certain of the content
N1000, roku1 XD/s, roku2 xs, roku3
speed range from ~18-20mbps
PM or tweet me if you want a channel added to my list, a correction or to update a developers' credit