So I got this Dell PowerEdge 6400 and wow. First, this thing is gigantic. Eight hot swappable SCSI bays in the front. Free is a good price ;)
Inside this thing has two Intel Pentium III Xeon processors, running at 750MHz each. Where you see the RAM is actually a tray of RAM. You can remove the tray and fill up 16 DIMMs. Hot swappable PCI ports too. Three redundant power supplies in case a tornado hits or something. I'm planning on getting a SCSI drive or two and getting Solaris running (or perhaps Nexenta).