I agree with TOO...new sockets and interfaces are constantly being released that it's almost impossible to build a completely future-proof computer. I made the mistake last year of building a S939 computer a month or so before AM2 was released, but oh well. Early next year I'll probably build a C2D computer after Intel's Q3 2007 price cuts....just don't worry about new things being released. I really don't see the need to replace my entire computer everytime a new part comes out.
Just to sum up...new parts are constantly being released and whatever you build will soon be outdated; it's the way of technology, which is why it's such a bad investment. Don't stress that there are newer and better parts available than those in your computer, as long as you're happy with your current computer's performance, there's no tremendous need to upgrade.