Static IP Configuration

I have a Win2k Server, configured with Static IP, DNS, and Gateway. Now something is wrong with that Pc and I need to swap that Pc with another one, but the new has Same type of Configuration pc. I did the SWap with a New PC, (Also Used the Same STatic IP, Gateway and DNS Configuration as the Old one had), Now I could Ping the External IP , but cannot ping or Find the Internal IP or get to that New Pc. Even the WorkGroup Name and ComputerName is the same as the old one. What should I do??? Any Help would be Appreciated. Thankyou!!