Give me the $$ needed and I'll build myself a pc for playing my media. Until then, I'll use the xbox 360's I already have in various rooms to stream my media. Oh wait, you'll need to give me $$ to build 3 pc's because I currently have and stream to 3 xbox 360's.
And wait again because I just realized I don't really want yet another device in these rooms, especially not one that could get viruses or have other problems. Sure my 360's can get the RROD or crap out for some other reason but I already have them and they work just fine right now. Why add yet another device to the loop when I already have something that works?
Maybe it's just me and what I watch but I don't have any problem with streaming. I'm using TVersity, Grid something or other, and PlayOn to stream from one of my pc's to the network. I can watch stuff on my pc's, Revision3 (DiggNation, Totally Rad Show), stuff on Hulu, NetFlix, and a bunch of other stuff. I also run SimplifyMedia and stream my audio collection to my iPhone when I'm out and get bored with Pandora.
What you seem to be missing is the current consoles ARE pc's. MS and Sony could both add other codecs and completely remove the need for transcoding and I would love that. Why do I need my computer to transcode videos? For divx the 360 handles it just fine. Why not add support for a bunch of other ones? And maybe that's the plan. Maybe that is how Windows 7 will handle streaming... you'll install an update for your 360 that will allow it to stream a lot more formats without any transcoding. That would be pretty sweet.