ok I ssh'd into my linux box and ran nmap -O on my powerbooks ip. The first time I did it I got the following results:
[root@www mvh]# nmap -O 192.168.1.100
Starting nmap 3.70 ( http://www.insecure.org/nmap/ ) at 2005-07-31 12:11 EDT
Warning: OS detection will be MUCH less reliable...