Your typical PC's hardware only has a lifespan of about five years anyways. Once you get to a certain point you have to replace everything. Mac user conveniently fail to mention that the new OS coming out from Apple wont work on anything older than a G4 meaning lots of Apple users who want to have the latest and greatest from Apple have to replace there entire system. Not saying its bad but thats reality as OS's mature older technologies get left behind.
Anyways back to my main point on upgrades, simply put there will be a natural migration to Vista because consumers will replace there computer and choose that path as an upgrade rather then trying to trump up there old computer to Vista requirements. Besides Dell,Gateway and other build PC's so cheaply now that it really is cheaper to buy a whole computer with the OS installed.
Today I took out my hard drive that has already has Vista on it, put hard drive into my computer. My "Windows experience" is 1. Due to my graphics which are at 1. This drags down my other Vista numbers for memory processor and hard drive which get a 4
Vista measures 5 computer components and your lowest number (1 for me) is your "Windows experience". To be fair this is with a 64mb graphics card, not integrated graphics on the motherboard