Active Server runs my home network and intranet. I have it set up with Active Directory, DHCP, DNS, ICS, and IIS with support for PHP and mySQL.
It's running on a 550 MHz K6-2, SOYO 5EHM mobo with 256MB of RAM, and a Diamond Viper 550 original TNT AGP graphics card. Also has a Sound Blaster AWE64 and 3Com NIC, and an external Diamond SupraExpress 56k modem (no broadband ;(). I originally had 64MB of RAM and it ran mostly OK, but since SDRAM is so cheap now I recently boosted it to 256MB for ~$70. My disk subsystem is a Maxtor 7.2GB + Maxtor 6.4GB + Seagate 2.1GB all combined into a spanned volume. I'll probably get a pair or quad of 40GB drives to replace those at some point in the future, 160GB of disk sounds cool.