Anyone know where I can get a good port scanner?

Im assuming a windows enviroment:

http://fury.rupture.net/

I'm assuming a Linux/Unix environment:

http://insecure.org/nmap/

Thanx for the replies,

Linux/Unix is correct I guess I should have specified.

Has anyone had any experience with nessus?
If so what is the URL.

Ever heard of Google? :)

http://www.google.com/search?q=nessus => http://www.nessus.org/

nessus is a nice program. Highly recommended... :)
Have a great day :)

regards
amar