Are you suggesting I build something like this: http://www.thebox.myzen.co.uk/Tutorial/Protection_files/shapeimage_10.png ?
With a 10k resistor in place of the 22R and a 0.1uF in place of the 100pF? Then use a 1k resistor as a pullup rather than a pulldown? Should this resistor be located to the left of "outside world" in the image from your site?
I know these are basics questions but this is really one of my first projects... I'm amazed I got this far... it's thanks to help on forums like this one!