Brandeaux, spot on. Now you've pointed it out I feel a bit stupid for not spotting it! I'd read about floating pins but I couldn't quite see how I'd left it that way. Note to self: pay attention to the schematic rather than getting distracted by the pretty pictures.
I'll be trying it with the resistor to the Arduino pin as well shortly.
DVDdoug, I am just about to google "electrical" centre to make sure I understand exactly what that means. I'll be googling "make before break" switches shortly too.
Have to admit that I'm still at the scaredy cat stage of the electronics learning curve for fear of breaking components, of which there seem to be so many and by different manufacturers, each one seems to need a different kind of voodoo to identify without the datasheet.
Once I've made sure I understand this switch properly, I'll be trying it the way you suggested (no resistor) as I'm a bit of a purist (programming background) and the fewer components the better (simple is always best as they say).
I went with the pull-down resistor for now to remind myself that I'm relying on it and that I must remember to make sure to put one in there. I wasn't 100% sure whether the pull-up resistors are internal to the chip or whether I'd have to put them on my PCB later when I'm soldering together the finished project?
If they're on the chip then I'll opt for the pull-up resistor when I assemble my final project as then I have less components but still have the protection of that resistor in there.
Roger that on using the delay() function, I wanted to check if the Arduino was somehow "stacking" the pin values (eg. a longer delay would still output the same number of 0's even with a longer time delay because they were being pulled off of a stack) but I realise now that there is no stack and when you read the value off of the pin then that is the current value.
Many thanks to both of you for taking the time to answer my noob question, it is very much appreciated.
Best,
B