I have been trying a few options since I moved to Windows Home Server and it does not support DLNA (as it did with Windows Media Player 11).
I found a good wiki page over at HillBillyHardware (?) that compares several different software titles.
My first test was TwonkyVision- which works pretty well, but also costs $40 (30 day trial)
Curretnly I am testing out FUPPES. This is a Linux to Windows port and there is not much documentation included with the software. There are setup instructions at hillbillyhardware and good documentation on the Wiki for configuring the server for a PS3.