What exactly have you tried??
First off, Turn the Windows Firewall OFF. Using more than One Firewall will cause problems, not more security.
Need to know the model Number of the Linksys Router as they are also known for problems. May need to Forward a Port.
#8. Who is your ISP?? More times than not, your ISP may be throttling P2P.
What Version of Java do you have installed?? The Newest Version is 1.6.6 I believe. Need only ONE Version Installed. Delete ALL of the others through Add/Remove Programs. Then Install the Newest Version.
Just a Few Suggestions.