You make some good points about the potential for dual core, Gatt. The potential -- much more than the current situation -- is largely what leads me to dual core in the new system I will build in mid-November.
Unfortunately, I can only afford to upgrade my system about once every 18 months to 2 years. (A wife, three kids, 2 dogs, 2 cats, and so on makes the computer budget much lower than it was when I was single.) The good thing is that, if I keep to this timeframe for most upgrades, my wife does not give me any grief when I buy top-of-the-line components. I'm a university professor and don't do much video encoding, though I do download stuff from my Tivo to my computer. I mostly do PhotoShop and other kinds of things that most tech writers do. And I am a casual gamer -- though BF2 is becoming more than just casual, for some reason.
For right now, I figure a speedy single core would be just fine for me and what I do. But I'm betting (about $200) that, over the next two years, more and more programs, applications, and games will come out that will take advantage of dual core. I can't say this definitively, but I believe that, over the next 6 months, out to two years, I will be happier with a dual core than a single core. If I'm wrong, well, I guess I blew $200...