At our place we use a CP243-1 module (6GK7 243-1EX00-0XE0) which gives Industrial Ethernet access that we use with Intouch. They arn't cheep in the UK but enables you to use the standard Ethernet card on the PC.
We use a third party driver (havn't got the name to hand, will have tomorrow) to handle the comms to Intouch on the PC. It works a treat and is very simple to setup.