Recommended
This is simply a summary of what i currently know.
April 2009, Top marks for the java ps3 media server package which is reviewed here
For 32bit windows i suggest trying out TVersity as it is pretty easy to setup and can do transcoding of your media on the fly which is a good advantage.
If you are like myself and run of 64bit ( x64 ) windows, TVersity will more than likely not work correctly (It seems like your network is lagging but really it is the application), this seems to be a known bug but the owners are not addressing it, therefor currently i use TwonkeyMedia. Sadly TwonkeyMedia is a non free ps3 media server. But it does have a 30day free test which is worth trying.
I am currently using FUPPES at home under windows 2003 server, and currently i recomend that as a opensource soloution.