OS 10.5 - Peer to Peer TCP/IP Network

I'm looking for a way to create a network [TCP/IP, or whatever else you recommend] between 2 - 8ish people (including me).

I'm sort of looking for a LAN effect, but across the internet to other computers.

I'm looking to use this for stuff like LAN gaming, connecting between computers, and just to know how this connection thing works for future reference.

Can it be done?
Is it easy?

I've searched on teh Google and it turned up results to system 10.3, no leopard.

Another question: Is it safe (secure)?

Thanks
Any questions, ask!

-kmkl