Slasher.
ZoneAlarm is a different kind of product. Nukenabber gives you a warning that someone is attempting to access certain ports (which you have to specify yourself as I understand it) and has tracing tools built in. As far as I know, it does not actually BLOCK access. ZoneAlarm is a software firewall. It BLOCKS access and alerts you if you want it to. Unless you have specifically configured ZoneAlarm to allow internet access to a certain program the firewall will not permit a connection - which stops Trojans and Spyware sneakily communicating behind your back. If someone probes one of your ports, ZoneAlarm suppresses any response - effectively your computer plays dead to encourage the kiddie to try somewhere else.
So far, I haven't seen any unfavourable comments about ZoneAlarm. Give it a try.