One web site had a PC133 256 MB stick for $55... but then, CompUSA turned out to have a 256 MB stick of PC133 SDRAM in stock for $59. Made by PNY, and PNY's web site kissed its pinky finger to heaven and promised that it would work with the VL400. I figured $8 was worth delay plus shipping, and so we put another $64 into the computer (for a total of $164; the 80 GB hard drive, old graphics card and old CD-RW drive were sitting around).
PNY was as good as its word; memtest86 saw 384 MB of RAM and it was good. That's close enough to being maxed out that I wouldn't advise getting another stick of 256 MB... better the money go elsewhere.
The Liteon CD drive may or may not have come with the Vectra, but in any case, it doesn't know from DMA, so that Sound Juicer blivets when I click on "play" for a CD in it, and is noisy enough that I worry about it, I will recommend to my friends that they ditch it and get a DVD burner; decent dual-layer drives go for $40 something these days, and can be moved to a newer machine if one wishes). The Sony CD-RW is slow by today's standards (8x, I think), but OTOH, I'm guessing it will be about comparable to their external CD-R drive if one is stuck with USB 1.1, and it does know from DMA.
Ubuntu Breezy Badger installed without complaint, and seems reasonably snappy with GNOME (though I'll install xfce4 and fluxbox in case they want something a little, or a lot, more minimalistic).
I feel much better now.