Recommendations for firewall/router hardware?

I need to configure a firewall/router box for a medium-sized office/factory, projected to grow up to 50 people over the next 5 years. The last time I did this I built a small rack-mount server box, small enough not to need case fans, with extra RAM (for the day), an onboard NIC for the external network and a 4-port 10/100 NIC for the internal subnets. But that was 14 years ago, and I imagine there are better options these days. Any suggestions? TIA, -- Bob Rogers http://www.rgrjr.com/