an old gray one with the multi-colored Apple / I want to use it on the internet. / PC card and USB. / power PC / color screen, preferably 16 bit or better, 640X480 or higher

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An old black one with a white apple?

Guide to G3 PowerBooks

These (barring the "Kanga" model) will do everything you want and more, are reasonably priced, use industry standard RAM SO-DIMMs and IDE hard drives & optical drive mechanisms, and are built like tanks. There are even G4 upgrades available for the Pismo models.

See the linked full descriptions of each model (top of column) for further information and buyer-beware notes.

IMHO any of the models you mentioned will be far too crippled for today's intarnetz