why do you feel the need to upgrade mate? you're only likely to gain slightly more range if anything at all imo.
how fast is the broadband connection? that'll always be the bottle neck unless you're transferring files from another PC?
if you put a separate card in the laptop, the switch becomes irrelevant. that's for the built in one only - just switch it to off and be done with it once the new card is in.

hope that's of some help.