On a side note, be careful with nmap, especially in a NATed environment. I recently had the joy of dealing with a situation as follows

An individual produced some code to test a network for hosts reachable, the network was I think a few /22s. The program was executed from behind a firewall/router, so for every test to every IP address, another slot was taken in the NAT table entry. Read X ports * Y hosts * Z networks scanned. Read firewall fall down go boom!. Read network admins very very upset, (spent a day dodging irate network admins spitting fireballs and lightning bolts from every conceivable orifice).

Moral of the story ... Be very careful playing with nmap, when you don't own the network, or understand all the happenings on your network. And don't be the guy that executed or wrote that code. Cause a whole lot of people will be really really unhappy with you.

/* And the Creator, against his better judgement, wrote man.c */