I feel like an idiot for having to ask this, but for some reason when I click to enable shaders in the options menu and then click OK, it doesn't apply them and un-ticks the Shaders option. Why?

If it unticks itself then you can't run shaders.
Try updating your graphics drivers.

Makes sense. what are the minimum requirements?

http://forum.toribash.com/showthread.php?t=154969
Look in the FAQ

Thank you! I'd looked all over for this, but couldn't find it.
+rep

Btw, if you want to know how to update your graphic card, go to http://forum.toribash.com/showthread.php?t=184246