Check the hardware compatibility list first. A. Intel Pentium - Avoid AMD and other clones. Get an Ethernet Hub. 4 to 8 ports, depending on your needs. No need for a smart hub yet.
Digital lines have multiple lines coming in on one wire.
Be aware that these lines usually mean contracts for a year or more. Consider what you can afford. Also get a block of IP addresses. By a Portmaster from Lucent. This is a single box that acts as multiple modems.