Seems to me that the solution to magic-proofing technology has already been given to us in the form of Butters and his GPS. By erecting a magic circle around it he was able to screen it from magical interference on a pretty serious scale.

Perhaps the best way to screen tech against magic is, ironically, a spell? Create a warding against magic around the object, then it should be fine? Especially if you leave it turned off while you're working so that it doesn't get fried while the spell's being cast.

And that "Understanding equals not explodey" theory is pretty interesting... makes for an interesting element to add into the game. (Tech Friendly as a stat, for example)

The other theory on why magic hates technology that made a lot of sense to me was (don't remember where this came from) that technology is based on the rules of physics, and magic tends to change them on a pretty frequent basis. So the problem with Dresden and a GPS is that the silicon chips in a GPS are counting that planck's constant won't be changing in the near future, and that the conductivity of silicon doesn't change. When a wizard enters into the physics, he might be changing such minor, unobservable properties ever so slightly without realizing it. Enough teensy little changes and "paf"... you're down one peice of tech.

Also goes a long way towards explaining why simple tech works better. The inherent necesary phsyics of a revolver are: "Springs pull things, levers work, gunpowder explodes, and metal is hard". Not exactly subtle or unmeasurable quantities there. Also, this and the "understanding equals not explodey" principle might work together, since once a more subtle law of physics is understood by the wizard, he might not make the subconcious alterations to it that another, less knowledgeable wizard would. (example: I know magnets hurt computers, and why. Harry doesn't really. So why would he bother to avoid making magnetic waves while around them?)