Hi Ian and
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I am not sure about the Mac as I have never used one
![Sad :(](http://www.pc-pals.com/smf/Smileys/Smileys/sad.gif)
Any PC capable of running windows 98 would be suitable as your always on one.
I have an AMD 450 running as a server which has been on almost 24 hours per day since around last November.
The limitations of an older/slower PC is possibly the restriction in the size of the hard drive that it can use, (65gig max in my PCs case).
A slow PC will still be faster than your network, so that isnt a problem really.
I do find it a bit frustrating at times altering stuff around on my server pc as its so slow compared to my main pc (Athlon XP 2100 + ) but as far as reliability and networking speeds theres no problem.
Hope this helps a little
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