I have two running networks one with a broadband internet connection, I want to connect the two networks so as to be able to share the internet connection. Any advice will be welcomed.

Assuming each network is using a switch, you can connect both switches together using a cross-over ethernet cable by connecting one open port on switch 1 to an open port on switch 2.

If one of the switches have an uplink port, you can use a straight-through instead and connect open port on router 1 to uplink port on router 2 (or vice versa).

The other option is to use a broadband router, such as Linksys or D-link or Netgear, etc.

You can install proxy server on one of the PC that has internet connection then share your internet connection to the other network using (NAT). In order to do this download or buy a proxy program for windows and configure it have a 2 Ethernet Card then connect the two network on the computer. And install and run the proxy program on that computer. Then setup the internet option of the IE to point to your proxy and waalaaH you have a internet connection sharing :) or geek style use linux or other Open Source system out there hehehe it can be done also