You certainly can use two NICS in one computer. In fact, it is necessary if your are running a gateway/proxy server so a single modem can be used by any client on your network. One NIC connects to the cable modem and the other NIC connects to your hub.
I was doing just this until a few days ago. I had one computer (450 Mhz PII) running Windows 98 SE ICS (Internet Connection Sharing). It worked great. A few days ago I replaced the gateway computer with a Linksys Router. This little Black (and blue) box (< $150.00) that makes no noise, takes up little if any space, uses inconsequential power, and requires no monitor/keyboard/mouse/etc., replaced an entire computer. It also works great and to my suprise, was effortless to set up and get running. A true no brainer.