That hardware firewall looks like a good idea for my old machine, once I have got the new one fully set up.

Main problem with the old one is that it will occasionally lock up completely, so that not even ctrl-alt-del would work. Theory was that it was a conflict, but I have never managed to track it down. It only ever happens when typing or scrolling, and ONLY in Microsoft Windows applications. It has NEVER hung up when using DOS, nor when using non-Microsoft apps.