Unless you're set on OS X, the Macbook or Macbook Pro are the way to go. But sometimes something will come along and screw all that up.
This time, it's HP's new HDX18t (HP's website is badly designed. It takes you directly to their store and offers specs and data all mixed together). I did a simple configuration on HP's store and this is what I came up with for less than $1950.
Still you have to wonder how anyone can resist this. Let me highlight this: Quad-Core, Blu-Ray, 4GB RAM, 512MB GeForce 9600M GT.
Just don't look at the Vista part. I also took at look at the lower end Macbook and compare it with the Sony SR and HP's dv3500t. A sort of preview as I decide on what upgrade best works for me.