jim.mar,
I have read this entire thread and don't believe I've seen anything related to what I'm about to ask...but, have you tried a straight connection through the modem only...instead of the router? Meaning the ethernet cable should run directly from the modem to the network card on the PC. Try that to see if any of your browsers work.
In addition...now, this is just me. If you're going to use the router...then that acts as a hardware firewall in itself. I would uninstall PC Tools' Firewall Plus and use Windows Firewall as my software firewall. However, you may want to wait to see what SuperDave recommends.
@SuperDave...at no time did I intend to step on your toes. I will leave this, now, in your capapble hands...
Keep us posted, Jim!