Slowly 667MHz DDR2 memory sticks will be coming from firms like Corsair, and probably also Kingston and others. Later even 800MHz modules will start appearing in 2005.
Believe it or not, it could be that we will get even faster parts later on and 800 MHz is the goal. It very much depends what Intel wants to do on this front. Intel is leading this game.Source: The Inq
Our memory fiends implied that the difference between DDR1 and DDR 2 might become more noticeable in future because memory timings will improve. The move toward 666MHz memory will increase this even more significantly.
So it's not all too bad if we're talking about DDR 2 and as once this becomes mainstream prices will drop.
If you want to go high end Intel Pentium 4 machines you have to use it or else you'll be lumbered with the "low end" Grantsdale 915P chipsets that work just fine with DDR1. And are much cheaper, naturally.