Great stuff. This is a blast to read. Hope you guys are all keeping your homeowner's/renters insurance paid up.
Here's what I'm running at the moment:
Custom-built PC (Athlon64 dual-core, 2GB RAM). My music server uses four 250GB disks running as a 1TB striped array with a fifth 250GB drive as a hot spare. I back up to a second RAID 0 running on a separate system; once a month I burn incremental backups to DVD for storage in a fire safe.
Right now, my library is around 18,500 tracks and 500GB, including around 15,000 music tracks archived as FLACs. The remaining MP3/OGG tracks are mostly archived podcasts, audiobooks, and vintage radio programming.
I usually run MM from a second system, where I also keep a master copy of the database. All of my desktop systems are networked using GB Ethernet, and the laptops are set up for .11g wireless.
My audio card is a M-Audio Delta Audiophile 192. I bought it for the hardware, and I stick with it because there isn't a company on the planet writing better Windows drivers for their sound cards IMO. I use the balanced analog outputs (1/4" TRS); the 192 also supports coax SPDIF output, but I don't use it with this setup and couldn't care less about it.
Integrated Amp: Marantz PM8003
Speakers: Boston Acoustics T-830s and a pair of Mirage M-230s in my office. If the T-830s ever die, I can always chop them up to use as firewood.
Turntable: Bang & Olufsen Beogram RX-2 (MMC3 cartridge). I see what replacement cartridges for this thing cost today -- when you can find them -- and I remind myself to take very, very good care of it.