Enumerate computers on the local network

[Pho Tek]

Hi,

I want to display a list of computers accessible on my local network.
My first idea is this:
1) Obtain my IP address & network mask
2) Then send a ping sweep across my subnet to obtain a list of possible machines.

At the minimum, I want to support SMB & linux machines.
Can anyone point me to resources on how to understand what ports can be used to identify a machine's Operating system? Thanks for any suggestions.

Pho