Ksk9 Hi.
First your java is out of date.
Now! Go to,
START/Set Program Access/Change or Remove Programs,
now completely remove all versions of java.
Re BOOT Your computer NOW.
Now! Use this Link to get (jre-1.5.11) Use the off line installer, NOT the (recommended) one,
Java SE Downloads - Previous Release - JDK 5
When Download is completed.
Disconnect from internet, close ALL apps n reinstall java.
Now this part is more involved, you need to portfaward your router & the nearest version I can find is WRT54G V5 so I can link you to that setup page
& maybe its the same for NAT/FW I dont Know.
You will have to make Different static IPs for each computer & portfaward both to router, using diffrent port No's.
Good luck
Your servant.
Peace.