"Why would anybody want to buy new PCs today?"
The answer used to be simple, at least in the MS world: you needed new HW to be able to keep up with the demands of the latest MS software. This has long been the quid-pro-quo driving the PC business: you preload our OS, and we'll both benefit from our forced SW/HW upgrade treadmill.
Now that XP and .NET are on the horizon, MS is building a revenue model far less dependent on growing OEM sales -- and will not need to offer OEMs the carrot of continual increasing demands on customer HW. I would be worried if I were a PC maker.

Giovanni