In this regard, the folks at Redmond are like software salmon (sperm?; even better) who've swum upstream as far as they're going to go. Sure, servers still have a reason to grow. Data centers demand it. But will desktops need quad-, eight-, or 80-core CPUs? I think not, unless one is intent on toasting English muffins.
In this regard, desktops are like audiophile-quality CD players, circa 1990 -- commodity items to be purchased with no more consumer effort than taking a quick trip to the local e-mall.
Moving forward, the platform we're going to be coveting -- and writing about -- is the "iPhone," whether from Apple or in a Symbian/Linux/Windows Mobile incarnation.
In software terms, there are two interesting trends, which underscore Vista's probable place as Microsoft's high OS watermark. First, Vista has essentially -- and at long last -- brought most of the features of Apple's Mac OS X to the Wintel platform. (Widgets/Gadgets, anyone?)
Secondly, Linux has effectively disintermediated expensive software vendors like Microsoft (much like bloggers have in some sense cut the rug out from under not quite as well compensated journalists such as myself, though I'm running hard to catch up :).
For Microsoft, it seems to me that the only real question going forward is, will the company's fate mirror more closely that of DEC (Digital Equipment Corp., to readers under 40), or of IBM?