Yay! Installing Ubuntu 8.04 instead of Easy-Peasy fixed my wireless access (basically by downgrading the drivers to ones that worked–theoretically I could have done that by fetching them and compiling them, but without net access I was missing too many pieces). Now all I have to do is never upgrade again and I’m set!
update: actually, it survived the first update. It claims to be current for the moment for the build, and wireless still works. Time to call it a success and a night.