One of the things I find interesting about Longhorn is that they're really trying to go where OS X was heading 5 years ago. Mac users experienced the shock of moving from something relatively lightweight like OS 9 to OS X, and the related hardware sluggishness associated with it five years ago. When Jaguar hit things started to actually feel 'right.' OS X has progressively ran better on older hardware, and one can expect even 5 year old machines to be in service a few more years, since Apple is still manufacturing machines running at 1.2ghz (the minis).
Apple was able to harness the latest technologies and still make a pleasurable experience on even meager hardware. 2 years from now OS X is probably still going to be acceptable on an 800mhz machine; meanwhile Longhorn will require what, a 3ghz CPU, and 128mb graphics card? PC components may be cheaper, but if one is going to run Windows on them, expect a much more frequent update cycle, since Microsoft needs to please hardware manufactures and help them sell more products.
From what I've seen of Longhorn so far it reminds me very much of the car Homer designed and had his brother Herb produce: tacky nonsense. I'm hoping Longhorn finally puts a nail in the Windows coffin, causing people to look at other alternatives to keep their machines up to date. Computing has really reached the point where one can easily say, "1gz is good enough for almost anyone." If you're running a sensible OS, not dictated by corporate pressure to sell more hardware -- such as Linux, I see no reason one couldn't keep a machine in service for ten years -- or longer. This is the reality Microsoft is going to have to face, so expect their lock-in tactics to become much more fierce. The relevancy of the traditional OS maker is diminishing quickly.
