Someone on an industry blog was saying that the problem with Windows Vista is that it's running on underpowered machines. I think that's true: if you spend enough money to buy a hot machine, you may have enough resources to run Windows Vista.
This approach has been a mainstay of Windows marketing since the mid-80s. I remember people installing Windows 2.0 on IBM ATs and, even though the 80286 was ~the~ hot chip in those days, an AT would drop to its knees and gasp for air under the resource load Windows presented. "Oh, no problem!" Microsoft said. "Just slip in one of these Mach-10 cards and you'll have all the power you need!"
IOW, you needed to spend $500 (in 1987 dollars) to repair the damage to your system caused by the $50 OS you'd installed. Or, you could keep running MS-DOS 3.1 and save the $550 in the first place. (Guess which I did?)
When I talked to MS developers I knew and said "Windows is really slow," they'd ask what hardware I was running. When I said that it wasn't the latest and greatest, they'd always say "Well, THERE--" with a finger in the air "--THERE is your problem: you need to buy faster hardware!" The idea that, since I didn't see Bill signing a check for me to get a faster machine with each new version of Windows, so maybe MS should try designing for the systems that were out there always failed to register with them.
It's 20 years later, and MS still hasn't changed a thing: they're designing software that requires a premium computer at a premium price to get the same ho-hum processing power we had had to begin with before we thought about upgrading to the next version of Windows.
I'll stick with WinXP, thanks. It works and it doesn't have the driver problems that Vista is renowned for. Judging by what I'm hearing about the upcoming Windows Longhorn, we may all be sticking with XP until about 2011.