I am a systems engineer, supporting Windows is my job. My understanding is that the DLNA service isnt provided by Windows Media Center.
However, at home, I avoid Windows at all costs. Even 7 with UAC turned on is a target for spyware and assorted virii. I did a demo last week for my CIO with 7 locked down (not even local admin rights) and I was able to hose it with spyware in under 2 minutes. If you are hell bent on using Windows for your home OS, you might as well drink the whole pitcher of MS cool-aid. I’ve tried the DLNA functions of 7, and they actually work quite well (WD Live firmware problems aside- btw, I’m not running the current firmware either).
I too have PS3 Media Server doing transcoding/DLNA serving to my WD Live and PS3…but I am using Ubuntu 9.10. It’s a fanless box running 2 NICs and Vmware ESXi (with one VM of Astaro (for firewall/web filtering/routing/DNS/DHCP services) and one VM of Ubuntu). Following the directions in the link above worked fine for my WD Live.