NAT with iptables / linux

[Christos Panagiotakis]

Hello people!
I just buy my first 16 static ip pack and I am wondering what can I do
to assign these ips to some workstation that I have.
Something like this

=========
=             =
=   Lan     =     == Linux Box === Modem/router === Internet >>>
=             =
=========

Lets say I have local ips like 10.0.0.0/24 and "real" static ips like
195.170.2.1 , 195.170.2.2 and so on....
And I want for every local ip to assing a static one.
In a few words I want every single workstation to have its own static ip..
A friend of mine told to that I have to use POSTROUTING and PREROUTING
and here is that I confused...
Anyone can help me / tell me what exactly have to do to make this work ?

Thanks in advance and forgive me for my awful english :-)

Christos Panagiotakis