Small network issues. Wired-has internet, can't "see" other computers
We have a small network in our office. Our "server" is actually an old PC with a large hard drive running Windows Home Premium x32. It is wired to our wireless router. We have 4 computers and a plotter that are connected wirelessly to our router. We limit connection to the router by mac address. The other computers run various versions of Win 7. There have been no issues until we replaced a computer with a new one running Windows Home Premium x64. We were able to log on to the router wirelessly, but did not have access to internet or other computers / plotters on the network. We tried hard wiring the computer to the router and were able to gain internet, but no access to other network computers. I'm a little limited in my experience with network issues; I've been fortunate that everything happened to work up until now. What would be a good way of troubleshooting the issue? What other information about our setup would help?