How does finder show a pc computer name but I can't ping it? I have a MBP running 10.6.  This is my first mac.

In finder, it sees the windows 7 machines and windows home server just find.  I can click on those computers and see their shares.  If I open up terminal and try to ping the computer name, it doesn't resolve.  I have had to add the computers to the host file.  I don't understand why finder appears to associate the name with the correct server from the terminal doesn't.  Can somebody explain it or explain how I can get the same behavior from terminal?
If a machine is found via Bonjour/multicast DNS, you may need to add a .local suffix to use the hostname in Terminal.  If it was found via NetBIOS (either broadcast or WINS), you may need to use nmblookup to get an IP address:

rushlight:10120 Z$ nmblookup mress
querying mress on 10.0.204.255
10.0.204.14 mress&lt;00&gt;
10.0.204.14 mress&lt;00&gt;