I've added another Dell PowerEdge system to my arsenal. You just can't beat these things.
After thinking (mistakenly) that I had fixed my old machine's lockup problem (or at least had worked around it by underclocking and using a generic kernel), it came back to haunt me with more lockups the following week. Instead of dicking around any longer trying to track down the hardware failure, I bought a Dell PowerEdge 420 for $330 shipped.
Now that Dell is fully operational, and is running everything the old system did.
I had toyed with the notion of migrating to FreeBSD, but when I woke up this morning to find my Athlon had locked up yet again - and that it wouldn't even *post* anymore - my hand was forced. I had received the Dell on Tuesday and had thrown a basic Debian install on it just to make sure everything was working, so this morning I pulled my old system, threw the old drive in the Dell, configured networking, and went to work.
Since it was a slow day at work, I was able to set up everything in short order. The Linux (and Unix) directory structure makes migration from one system to another truely trivial. The Debian package system makes installing all the software I needed equally trivial. All told, the migration cost me maybe 2 hours of actual work, and for most intents and purposes the system picked up exactly where the old one left off.
So cheap, so easy. Dell + Linux - you just can't beat it.