I just found out about sharing media player libraries using Win 7 yesterday from Lifehacker. I just tried it. And I'm REALLY impressed. Especially with the video. I just got done streaming an HD episode of TopGear from my house to work. It was perfect. And it allowed for instant playback after seek, i.e., no buffering. Seriously, it was basically like I was sitting at my home PC.
This is the kind of thing that makes me wonder why Microsoft doesn't have stores and genius bars and why they only have developer evangelists. There's so much good stuff that goes hidden even from self-proclaimed uber-tech-gods like me.
On a side note, since it was streaming at 4x my current maximum bandwidth, it caused me to realize that my cable internet service was just upgraded to DOCSIS 3.0. Woo hoo! Looks to be 20'ish down and 2'ish up--at least as best I can tell using remote desktop and Speedtest.net. Not amazing, but compared to 6/384, it is like a whole new world just opened up.