I would go for a software based solution on each pc if this is for the home environment. Something more advanced would take more hardware than you might be able to fork the money out for. Have a look at this....
http://www.protect-me.com/ You do not have to use this, but get to grips with what I am talking about and look for a solution that suits your environment and you pocket. Linux would be the best and cheapest, but not the easiest.
Cheers
<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Ltheron</i>
<br />If I use the ethernet option, is there a way to control internet access to certain pcs?
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He who does not understand the value of war at the right time, cannot comprehend the value of life at any time - Anonymous