I reached the same conclusions a week ago and decided to write up a tutorial on how to make encrypting email as easy as possible.

For those that might be interested, here is a (hopefully extremely easy to follow) tutorial on how to get email encryption working on a Mac running Mountain Lion:

https://medium.com/open-source/7151e454ed93

For those that want secure instant messaging the answer is much simpler and better. Get a client that supports OTR (Off The Record), on the Mac that's Adium. So long as you've clicked the "generate key" and both people have OTR installed, messages are encrypted.