ps3 media server is feature heavy and in JAVA in other word it a resource hog but it does transcoding really well! It all depend on your platform I guess. On a Linux dedicated files/media server nothing beat Fuppes or Mediatomb both are pretty lightweight. On windows I used TVersity.
I'm on a Mac and found PS3 media server to be pretty useless and at times confusing.
I find Vuze to be the best program. It downloads torrents, and is a media server/transcoder all in one.
What's nice about it is that you can DL your files and set it up so that your files will automatically be ready to be played on the PS3 as soon as they are done, so you can set-up a bunch of movies to DL, and just chill and relax in front of the TV and watch your newly DL'ed movies right after another without having to go back, in most cases, and fuss with your computer.