So; results of the experiment...
It works! I successfully ran the IDE, edited and download BLINK...
I was able to get Ardunino-0015 running on my PII 266MHz W98se system with only minor difficulties (most of which were caused by not having dealt with USB installs on W98 in a long time.)
I had to download and install java, of course.
I had to download the w98 ftdi drivers (which are not included in the Arduino distribution, but are still available from the FTDI site.)
It's not entirely without "quirks": for each "background process" that the arduino starts up (compile of a half-dozen files, building libraries, link, etc) I got a visible pop-up DOS window (hmm. But I don't recall seeing any for the "extra" library compiles. Interesting.) No big deal...
A 266MHz PII seems a lot slower than it used to 