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I think if Ubuntu Live only need 700 mb's then it should be able to be run from a USB.
Marty, Welcome to PortableApps.com
for previous discussions on the subject.
Using other search criteria in the search box above (e.g. just "ubuntu" or "ubuntu flash" or "ubuntu portable" etc,) will yield even more results.
Things have got to get better, they can't get worse, or can they?