If you want to simulate some (wired or wireless) Network you can read and use this projects:
1) Network simulator NS2
2) OPNET (You have to be registered)
If you want to Monitor and Manage small/big networks you can install:
And if you are looking for the best Linux based operative system, stop and go to:
6)UBUNTU (I recommend 7.10 Server Version)
Cooming soon I'll post some tutorials and HOWTOs....