You can read up on DLNA here:
Digital Living Network Alliance - Wikipedia, the free encyclopedia
It is included in Windows 7 so you are already all set to go in you wish to stream audio/video from your PC but you do have to get in the windows 7 control panel (see below) to set it up.
Control Panel\All Control Panel Items\Network and Sharing Center\Media streaming options
Spoke to soon. Just double checked my setting on the PC. Apparently I had not gone into Media streaming options. I have now set that and am currently listening to music on my AVR from my PC, graphics and all. Thanks so much! This part of my journey is almost over. I will have to centralize the music on my PC a bit better and begin the ripping of ALL my CD's. The best part of this is that both my AVR's should be picking up my PC. I'll check my other later today.
Now I will continue to look for a way to play music directly from an external hardrive to my AVR's. If I don't get anything to work the way I want at least I have this and most importantly I do have random play. LOL