An after market third party USB dongle can be used on the iMac G3, assuming the iMac is running MacOS X 10.3 (all models will run this, including the Caddy Loading iMacs)
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An after market third party USB dongle can be used on the iMac G3, assuming the iMac is running MacOS X 10.3 (all models will run this, including the Caddy Loading iMacs). However, no iMac G3 (or iMac G4 for that matter) can use an airport express card. These computers are all Original Airport card only (802.11b). A third party USB dongle will provide Airport speeds equivalent to 802.11g.
An after market third party USB dongle can be used on the iMac G3, assuming the iMac is running MacOS X 10.3 (all models will run this, including the Caddy Loading iMacs)
ref: http://www.forevermac.com/1998/05/imac-g3-233-mhz-dekstop-computer/