Update to Home Media System

I have been a Mythtv user for over 4 years.  I built my first mythbox (like most people) from a spare PC I had.  I think it was version 0.13.  About a year later I went all in and purchased a top of the line (at the time) machine specifically to dedicate to mythtv along with the brand new (and at the time threatened by Congressional extinction) ATSC HD OTA card.  After hours of trials and tirbulations I finally got the entire box working the way I wanted and was able to view all of my photos, listen to all my music, record and watch TV shows, and watch movies ripped from my DVD collection.
It worked really well, although there were two things I always wished worked better.  First, it was a noisy system and having it run in my theater room always meant you could hear fan noise in the quiet parts of whatever I was listening too.  Second, since most of the ‘master data’ (songs, pictures, movies) was on my main system, I had to copy (at first manually on an external disk and then later over the automatically over the network) everything to my mythbox to view/listen to it.  That caused a latency problem (it took a long time to get data there, regardless of the method) and a replication problem (I had two copies of everything – wasting space and sometimes causing conflicts on which was the ‘right’ data).
My mythbox ran with almost no system level intervention for more than 3 years.  Then all of the sudden about 3 months ago the power supply died and took the motherboard with it.  I didn’t have time to fix it when it went south, so I pulled it out of the rack and it’s been sitting on the floor of my office ever since.
In the mean time, I think a viable replacement has emerged in the form of my Xbox 360 and Tversity.  I have been playing around with various methods to stream things from my PC to my Xbox 360 since I picked up the wireless adapter for it a couple of months ago.  I even considered getting one of the new Media Center PCs when they have cable card support (which from what I’ve read may be a while).  However, with the May 7 Xbox update and the new version of Tversity that feeds the Xbox the correct information to stream from folders, I may not need to do any of that.
Right now, I have a 500 GB external disk connected to my main PC that has all of my media on it.  That PC has Tversity, ffdshow (the older .802 version that Tversity / Xbox seems to like better) and the Xbox 360 path on it.  From my Xbox, I can listen to all my music, create and edit playlsits, watch all of the videos, and look at all my pictures.  No copying anything over, no noisy PC running in my media room.  Sweetness.