Look at Gmail to see a case study of encryption for email traffic. Generally, it's a good idea, as a way of increasing the security of your information on an untrusted wireless network, but this is not a way of deterring spammers, and your email headers are in no way obscured to the Gmail servers. Two different issues are being confused here - what you seem to be describing is similar to the mixmaster system - a system, by the way, designed so that people would not be able to return your emails, since all the header information is changed completely. Anyway, the mixmaster system is pretty unreliable at the moment.

Encrypting email traffic will not reduce spam, it will only increase information security. IMHO.

Generally, I think that as long as making a network "secure" involves as much studying, learning, and effort as it does now, most people will not do it. And so we end up with the situation we have now. This can't really be blamed on Windows. It's a people thing. Like Bruce Schneier says, security is a process, not a product.

Back to the topic of cyber crime, you folks might find this interesting, if you haven't seen it already.

The way internet access and email is currently done by ISPs? No. But if they took the simple step or requiring separate passwords for connecting to their service and using their email servers, it would be both easier to stop the theft and to catch the thief.