I'm not so sure of that. It's important to learn how a real computer works -- not down to the level of the copper on the board, but the basics of what a pointer is, for example. While turning machines and real computers are largely equivlent after an isomorphisism, it's a fairly harsh isomorphisism. Understanding a turing machine won't allow you to grok pointers, because turing machines don't have pointers, or, indeed, RAM -- Random Access Memory. Memory on a turing machine is purely serial, and infinite in extent.

On the other hand, the differences between the arch of an x86 box vs a PPC box are at a level of detail to be irrlevant to most perl programmers.

Knowing how a water pump works, even though a water pump is isomorphic to a heart, isn't all that useful for a heart surgon. OTOH, knowing how a rat's heart works would be very useful even though there are differences between a rat's heart and a human heart.