I'm sure this will be an easy question for some of you champs.

What I'm looking for is the cheapest, simplest box which will stream content from a PC in room 'A' to a TV in room 'B'

I am currently using a PS3 to do this from room 'A' to room 'C', and an old Xbox with XBMC for room 'A' to 'B'.

I want to retire the Xbox as it's very loud, but the replacement needs to meet the following requirements:
(in order of importance, everything is negotiable)

Cheap: Ideally less than $100 new
Simple: It needs to be easier / as easy to use as a PS3 or Xbox, for W.A.F* reasons
Small: So it can hide behind the TV in room 'B'
Power Efficient: Don't want to have any noticeable effect on the power bill, but I assume the Xbox isn't too economical anyway.
and Preferably a name brand, I value the ease of being able to walk into a store and having a decent warranty/support if necessary.




* Wife Approval Factor