is this GC79 just GPRS?
(no fancy EDGE or 3G?
) then maybe you're better off with a nokia D211... that too knows GPRS+WLAN
i have one and it works fine in the j720.
i think the GC75 has hpc2000 drivers though but that maybe doesn't even know gprs
(can't remember for sure now!
)
another idea: ifyou already bought the card you can try the nokia D211 drivers, who knows ...