Today I went to Amherst Computerworks and bought a 128meg RAM module for revo. I pulled out the old 32meg module, moved the old 128meg module (which is 66mhz RAM) into the first slot and put the new module (which is Crucial 133mhz RAM) into slot two. It booted up with the new memory and seems perfectly happy. It seems to thrash a lot less doing stuff, so I think before the system was a little memory starved. Running Window Maker, Mozilla, and xmms, I still have 64meg of free memory and 0meg of swap being used. Now the question will be whether the system will stay up without getting a random kernel Oops after a while.
The fellow at Amherst Computer largely concurred with my diagnosis. I was careful to try to describe symptoms and not rush to describe the conclusions I had drawn. His other hypothesis was that the powersupply a little marginal. I might be more inclined to agree with that, especially if it was a problem which had developed over time or if it was correlated with events that might put additional load on the system (like spinning up a CD). Since it doesn't I'm less inclined to believe this line of reasoning. He added that, if it was the powersupply, there wasn't really anything else to be done, because it was a custom part and that standard powersupplies wouldn't fit in the case.
When I buy my next machine, I'll definitely consider Amherst Computerworks -- they seems like good, competent folks and, in our department, we have enough experience to know that they stand behind their work.