Are information-retrieval tools like google set to diminish human memory?

There's a gimmick in Jonathan Lethem's dystopian noir first novel, 'Gun with Occasional Music' whereby people start developing chronic amnesia and carry all their memories around on little electronic personal organisers. When I read this I thought "hoho, a nice Phil Dick type metaphor for contemporary schizo-culcha". But more and more, I find my memory for insignificant details going. The other day I couldn't remember the name of ManU's slack-jawed winger (Luke Chadwick) so I googled it. Worryingly, I find myself doing this more and more, and kind of relying on google/theinterweb rather than bothering to try and remember things. Does anyone else find this, and shd we be worried? (cf: nobody knows each other's phone numbers any more, because we rely on our mobile address books; cf also: Plato's antipathy to writing, because it would diminish people's ability to memorise things)