I'm ripping some of my HD DVD movies (Bourne Ultimatum, Smokin' Aces) to play on my WDTV, the few I've got have DD Plus 5.1 audio which doesn't play as 5.1 through my WDTV (WDTV seems to output it as ProLogic according to my Amp) , none of my software seems able to modify it from DD+ 5.1 to regular DD 5.1 , Any ideas ?

I'm ripping some of my HD DVD movies (Bourne Ultimatum, Smokin' Aces) to play on my WDTV, the few I've got have DD Plus 5.1 audio which doesn't play as 5.1 through my WDTV (WDTV seems to output it as ProLogic according to my Amp) , none of my software seems able to modify it from DD+ 5.1 to regular DD 5.1 , Any ideas ?

I had that problem with a movie I downloaded, you have to extract the file using MKVextract assuming its a MKV. Then audio file will probably be a E-AC3 file so extract it then use this software http://www.afterdawn.com/software/audio_software/audio_tools/ac3to.cfm to covert the file into a regular AC3 file then remux with the video and your set.

Thanks Jruc03,
I downloaded the Eac3to software, fiddly to use with command prompt and lack of instructions with it, but a Google search for the command prompts to use and I got it to work successfully.
My method was to rip my hd-dvd with Anydvd, demux with EVOdemux which created VC1 (video) and .mpa (audio file), I ran it again through tsMuxerGUI and that created an .ac3 from the .mpa file, the .ac3 was actually a e-ac3 (Dolby Digital Plus 1536 kbps) file that Eac3to converted to a proper .ac3 (640 kbps) which was remuxed back the Bluray with tsMuxerGUI then converted to an .iso with ImgBurn for the WDTV.

User Interface is available here (http://forum.doom9.org/showthread.php?t=135095) to make Eac3to easier to use. Eac3to can be used to convert from DTS to AC3 amongst other things - very useful.