Well, I downloaded VO and created a trial account, but the program won't log me in. I type in my username and password and it says 'connecting' until the server times out. I guess I am doing something wrong?

Check your firewall settings, and disable PeerGuardian if you are using it. Regarding firewalls, you might have to add Vendetta as an "allowed" program under GUI-fied firewalls (ZoneAlarm, etc.). The iptables rules is below, if you're on a *nix system:

-A OUTPUT -d 204.11.209.42 -p tcp -m tcp --dport 21024 -j ACCEPT
-A OUTPUT -d 204.11.209.42 -p udp -m udp --dport 21141 -j ACCEPT

(requires that you have a rule in INPUT to allow related packets)

Also, check your "Network" options. Try setting it to "Compatibility" mode.