Don't do it. Don't drink the kool aid. Most people I know (normals and IT geeks) are upgrading to WinXP from Vista due to poor performance - even on quad cores - things like the all day file transfers, poor driver support, and user complaints (in the corporate sector) are prompting the move back to XP. I bought a dual core machine with 2Gb ram for my wife and after two months of tweaking and another two months of heavy usage - she is begging me to put XP or Unbuntu on the machine.
Vista - "The ME version noone wanted"
I plan on leaving this world the same way I came into it - screaming and covered in someone else's blood!