Reposted from another thread, more appropriate here since this is now my problem:
I'm sorry to report that I get a kernel panic after about 400 MB network transfer following my "solution" above.
Apologies, to all, it really looked as if it was working. I presume there's a bug or incompatability in those Ralink drivers.
I don't know what to do now, as I can't even access my WPA2 wifi with the default drivers.