It turns out that my vast personal estate includes a single 386 machine and three 486 machines. I don't discard them simply because it is irreponsible to throw computer components in the trash. However none of these machines has felt the warmth of an energized power cord in a very very long time. If I recall the bios on these machines was limited to 64 MB RAM or less, as you say. Since RAM in those days cost about $50/MB I expect that these machines all have much less than the 64 MB limit. I'll guess that one has 16 MB RAM, and the other two have 8 MB RAM.
At least one of these machines was used to run Linux. In fact if I booted them up they probably have a working install of a v1.2 or v1.4 kernel. Slackware. I can't remember how large the hard disks would be. Probably 100 MB. I know that they each have a Linksys NE2000 Ethernet NIC. I had them all networked once upon a time.
But I wouldn't bother to do anything with them now. They're not worth the electricity that it takes to run them. They're just waiting for me to take the boards to a computer recycler. Maybe the hard drives as well. I can put new power supplies into the cases so I can reuse them.
The machine that I'm currently putting together is an HP Pavillion 350 MHz AMD K6(?) with 256 MB RAM that I purchased in 1998. THAT's going to be a firewall. The disks are just big enough to be useful. One disk is 13 GB and the other is 9 GB. That's just big enough for a SuSE installation with graphical environments on the larger drive and extensive log space on the smaller drive. That's about the oldest/weakest computer that I would bother trying to use for anything. I'm going to put SuSE v9.2 on this machine. I'm tempted to try Debian on it. Apparently the "sarge" release allows you to choose between kernel 2.4 or 2.6. This old box would be a good testbed to run performance tests comparing the two kernel versions. I may do that.
In summary and in response to your question my 386 and 486 computers will never again be powered up by me. They may be of use to someone in Romania but they don't have the enough horsepower for me to bother with them. :-)