Help with blocked ports/Synergy

Hello, can anyone help me figure out what is blocking the ports I need to use Synergy. I have tried setting it up with both the firewalls up and down, I am not able to establish a connection. Same problem with Multiplicity.
I have a Dell Inspiron 6000
a dell Dimension 4300
both run XP
I have Comcast Internet
a Linksys WRT54G, Motorola modem and a Vonage router, with Vonage behind the Linksys (although I have tried both behind and in front of)
my computers are networked, file sharing/printer sharing and pinging each computer works fine
using the telnet command does not establish any connection on port 23 or 24800 (the default port for Synergy)
I use Iolo firewall, anti virus and threatfire on the laptop
Webroot on the desktop