The extra info you just gave me, tells me you have 2 problems.
One, You should only have one version of java running in Add or remove Programs, so delete all java you see in (Add or remove Programs) & use this
link to get the "Java Runtime Environment (JRE) 6"
http://java.sun.com/javase/downloads/index.jsp
Next, as you have TWO computers on one connection, You must make 2 diffrent static IP's first then, in L/W 2 diff listening ports n portfaward both
Sorry routers are not my bag.
Peace.