See what ports are open on your PC?

As we connect to Internet all we care (or should be) for the safety of our PC.  The ABC's of security are to enable firewall functionality router And above all have ADSL installed personal firewall. However, just take all these precautions, can we be sure that no one will access the PC from the Internet? Unfortunately, it is possible to be 100% safe. However, there are tools that allow us to