You can usually share a connection with just an ordinary hub, as long as you don't want to share files or printers. You can do more than that though.
With the new house, I just set up a four-node network with my new athlon 1700xp/GF3 followed by a 800 p3/GF2 GTS-v($50 at Newegg - great value), and a celeron 900/GF2 GTS-v. All these are in my "office"

The wife's networked system, on the second floor, is a P3 500 with a GF256. All are set up with UT2 and the office machines have Midtown madness, Alien v Predator 1, and AH for a nice Lan party option.
For "house" controllers I bought 12 Saitek action pads which I found on sale at Extreme Computing for only $5.00 a piece, I figure there will be some replacemts needed down the road so why not stock up

The network is maintained with file and print sharing by a Sohoware router/firewall that works great with a lot of options (I picked it over the linksys after reading all the reviews I could find.) I just got in a print server from Sohoware which I'll have to set up so that any machine can print at anytime without having to turn on my main computer. Cost wise, about $1000 including all the new components for my main machine

Things sure have came a long way since I first spent $1800 on that 286/12.
Charon