im pretty sure that you have to have dsl (or anything faster than dial up) in order to network computers. someone correct me if im wrong.
Technically wrong but I see what you are saying...
you can network computers regardless of the speed of your internet connection... all you need are two network cards (one in each PC) and a cable to conect the two, (if you're only using two machines a crossover cable is fine)...
I see what you meant though.. if you are on dialup, then there is little point in sharing the internet conection between the two machines, whilst it is *technically* possible, it'll work so slowly that you'll just recieve timeout messages most of the time.