Polling / Interrupt mode

Hi,
I am new to the world of network drivers and would like your advice
before starting off on a  project.
I have a 3Com vortex ethernet card and would like to use it in the
following way. The card is set up in polling mode and a kernel thread
keeps on calling the device driver polling method to read packets off
the card. But just this scenario leads to wastage of CPU cycles when no
packets are actually being transmitted . To avoid this , when the
polling method returns no packets; the card is switched back into the
interrupt mode.After the first interrupt received we switch back again
to the polling mode.
Is this a feasible idea?
Also, the basic aim is to reduce the number of cpu cycles spent in
polling the network card under idle conditions. Are there any
alternative solutions for this?
Thanks in advance
Puneet