No, that isn't what i'm saying!
I'm saying Workgroup Networking is different from UPNP.
With Network (AKA Workgroup Networking) the Med "shares" the remote disk, it accesses it using ithe Med's own File Manager, and can maniplate the files as if they where internal, including Play Folder.
With UPNP the Med gives control over to the UPNP server, and it's File Manager. You see similer information, and use similer point and click access, but you actually interacting with the UPNP Server's File Manager, which has no idea what Play Folder is!
UPNP is easier to use than Network, but you are limited to Explore Folder, Play File, and then of formats the server understands.
The good news for windows 7 users is that Version 4 now communicates that a Med can play H264 and VC-1 to Windows Mediaplayer. So you can now stream these files via UPNP without them getting converted to Mpeg2.