Good news for consumers and bad news for retailers, with the business release of Vista behind us and the retail release on its way, there is a veritable horde of Vista-incompatible hardware still stocked in inventory in businesses all over the world. From video cards to motherboards to network cards, many manufacturers aren't going to concentrate on writing drivers for old hardware, especially with the high cost of WHQL. The concern for retailers is that after Vista is stock on desktops, the sale price of non-Vista hardware will plummet, making it effectively worthless. That fear extends even into hardware that supports Vista, but only minimally:

The sources predict that even products that only support Vista basic may quickly fall out of favor in the market as consumers are likely to be more eager to experience the full multimedia functions promised by Vista.
For the desktop enthusiast, this might be a great thing. If you are looking to build an older machine that won't be requiring Vista, prices may be so low that doing such, even with new parts, is dirt cheap. I for one am looking forward to hardware prices dropping. It's unlikely these will affect CPU or RAM pricing, and won't change the prices of newer hardware.