look up Plex media server. I've gone through a lot of options for streaming pc content to the roku and plex is the best because it transcodes on the fly, so you don't have to worry about having the right filetype. Still a bit buggy with some files but it mostly works like a charm if you set it up right.
The channel is private so go to the roku site and add the channel code "plex"
http://www.plexapp.com/
edit: and I just updated the plex software and found there's a beta with working hulu support (no need for hulu+ since that's all roku supports otherwise), score.