tversity works decent with sd content. With 720p & 1080p content tversity was lagging on me.
I kept getting constant buffering due to the re-encoding that needs to be done. Maybe my machine is a little to slow for that(p4 2.4ghz) but I found if you have a spare external hdd, reformat as fat32 and toss all your xvid media & h264 videos on there, it works fantastic.