Hey, it worked!

Well, would you look at that. You really can put an Ubuntu LiveCD into your machine, boot, and off you go (for a somewhat slow trial, at least). Now, I've heard some users had hardware problems... perhaps my laptop is old and generic enough that pretty much everything works. At least it recognized my network connection automatically, my home network is flaky enough without trying to sort things out in Linux. And (having backed up my key data) I'll be taking Ubuntu for a test drive for the next couple of weeks and see if it works for me.