The biggest problem by far is there's no way to run an IP filtering app like PeerGuardian/MoBlock globally and the Linux iptables firewall at the same time."12. Bad security model: there's zero protection against keyboard keyloggers and against running malicious software (Linux is viruses free only due to its extremely low popularity)."
If you integrate PeerGuardian (MoBlock) into iptables,you lose the basic firewall protection.You can't use both at the same time as in Windows. Major suckage.
The Iptables firewall is powerful, but does not offer per-application rules. Compared to a good firewall for Windows, iptables feels like swiss cheese.
When you use Linux, keyloggers,malware,spyware or any f**** program can send stuff over port 80 without your permission and you can't do anything about it...