I have no problems using the windows media center pnp (my server is a windows machine so it was the most hassle free setup) even for 1080p streaming. Anything in mkv or other unsupported formats I just convert, as mkv's have generally poor support not just on the PS3 and I have more than one device I stream to.
With normal divx or xvid files you'll always have the best compatibility and you'll not have to worry about transcoding on the fly which is very CPU intensive. Using dynamic playlists will help keep things organised and it'll always just work.
I've no problem using this server though I've tried it a few times but I need an idiot proof, no hassle solution as I'm not the only one watching my media. Both this one and TVersity work but their problem is in the setup and configuration which can be very complicated and if you want to transcode 1080p movies on the fly you'll need to have a very strong CPU sending.