OK...
Microsoft CANNOT make new version of Windows every couple of years like Apple can. First of all, there are far more business users of Windows than Mac. Why does this matter? Many large businesses do not want to spend the time and money to upgrade thousands of computers every couple of years. Throw in indirect costs like training, and it's easy to see that Microsoft won't make a new OS every couple of years.
Second of all, when's the last time you made your way to Best Buy (or Newegg) to buy a new graphics card, processor, and motherboard for your Mac? Oh yes, you can't. What about for your homemade Mac, one you made from all the components you bought. Right, forgot that you can't do that. Microsoft must test their software to ensure acceptable compatibility amongst the thousands and thousands of hardware pieces available for PCs. Apple can be more rapid with their Mac OS releases because they keep an enormously tight control on the hardware used. They don't need to deal with crappy 3rd-party drivers or other such sources for crashes as much as Microsoft does.
I stiil laugh when I see Micro$soft... What's up with the $? I find this funny coming from some of the Mac-fanatics given how Macs TEND to be more expensive than PCs (for equivalent parts). Maybe I should say I don't want any Mac$.
Of course hardware requirements would be higher with Vista than previous versions... Computers have gotten progressively faster and more powerful since the release of XP, so wouldn't you expect the new version of Windows to utilize that power? Couldn't you equally say "Man, why I can't I run this on my PC with a 486 50mhz processor, 4mb RAM, and a 50mb hard drive... It ran Windows 3.1 just fine, so why the high requirements for Vista?"... Oy. Nobody's forcing you to upgrade... If you don't want to upgrade because the requirements aren't met on your PC, then don't upgrade.
I wish we were all more reasonable about this. Without Microsoft, the computing industry would not be as far along as it is now. Regardless of whether or not you hate Microsoft, it's tough to deny that they played a massive role in computing advancements (and getting computers "to the masses"). I'm NOT saying Microsoft is the best company in the world, but it's foolish to think they're the worst.
P.S. -- I can go to a Mac review site now and find several front-page articles about how great some Mac products are... Wouldn't you expect some pro-MS reviews on a site called pcworld.com?