First off, I'm putting rules together for my own RPG, but I think this is something that could apply to any RPG...
So i'm throwing some thoughts out to see what you folks can come up with...

Majik is often seems as incompatible with hightech.
For my setting, nature is strong where the presense of man is weak - hightech aeroplanes are vulnerable in the air, hightech ships are vulnerable when at sea, etc.

Also, the more powerful a majikal person is, the more susceptible to the effects of majik.
Also, the more powerful a majikal person is, the more they affect hightech items.

There's more, but this is a taster done while I'm bored at work.

Thoughts ?? Ideas ??

Why are you spelling it like that?

Because of the witches.
Or maybe that should be wytches