How are the PC's connecting to the internet??? is it via a router or are you using internet connection sharing on your windosw pc?
what are you looking to get out of the pc's seeing each other? file sharing? if so you need to install and configure samba.
Post more of what you are looking to get out of the connectivity and your current setup then i can help you.
Running Fedora since FC1, running Redhat since 5(not EL).
Registered Linux user number 485853
Rossendale and East Lancashire (UK) LUG http://www.rosslug.org.uk