No one here's ever tracked down a 16-bit PCMCIA-to-USB adapter. If you ever wanted to go that route, you could use a PCMCIA-to-CF adapter and then a CF-to-USB adapter inside that. But I'd go with the Socket CF Bluetooth receiver as well - I've had nothing but good experience with mine.
(It will work inside a PCMCIA-to-CF adapter.
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