At work we use an old (10 year old) linux box with 4 interfaces to act as router/firewall for the network. There's never really been a need to change it since it's stable and handles all our needs.
I'm wondering, though, would replacing the network interfaces with newer ones provide a benefit? Besides the obvious bandwidth increase (eg. 100MBit to GBit), would there be a latency reduction, or do newer cards pretty much do the same thing as old ones?