Nmap only gives you information on the version of OS and of network applications.
e.g.
nmap -sV 127.0.0.1
Starting Nmap 5.00 ( http://nmap.org ) at 2010-12-01 18:28 GMT
Interesting ports on localhost (127.0.0.1):
Not shown: 997 closed ports
PORT STATE SERVICE VERSION
631/tcp open ipp CUPS 1.4
2000/tcp open callbook?
24800/tcp open kvm Synergy KVM
See "Remote physical device fingerprinting - Tadayoshi Kohno, Andre Broido, kc claffy"