I was trying to bring to light the fact that OS consumption of resources has jumped very much so since the XP era, and I doubt security measures is the reason behind that. While I understand that XP was designed for 'dinosaur' systems, on the other hand... most people want their hardware's juice that they pay a pretty penny for to be used on games and applications, NOT to have the OS suck down 25% or more of each continuously. Something isn't right with that when compared to XP's considerably smaller 'footprint' than both Vista and 7. And I guess the main point is that if this is how it's going to continue, eventually we'll have to install 30gigs of ram and several CPU's just to get the damn OS to boot.
I guess the reality is, first, that your OS shouldn't be consuming more than 1% of CPU during normal usage - if it is, you have a problem to troubleshoot. Vista, Win7, and higher will *use* RAM as a cache to supplement/speed disk access, but only insofar as the user and his or her apps do not need that RAM (they are given back if that is the case). As to hardware specs, Windows 7 (and now Windows 8) have lower hardware specs than the "big jump" of Vista, and in fact Win8 will run on low-power, low performance ARM devices just fine.
I'm not sure I'd agree with you that the future of computing is 30GB of RAM anytime soon

, but several CPUs are likely (having a lot of slower CPUs is much more preferable to having one fast one). Again, you must remember that a good deal of the codebase of XP is based on the original Windows NT (which was NT OS/2, even, before it got the "Windows" branding), which has it's root in the late 80s and (very) early 90s - and originally designed around the Intel i860. That codebase bloated (and ultimately became Windows Server 2003 SP1 and SP2, which Vista, Win7, and further OSes have been based on) with the additional security added in Windows XP SP2 - if you want to realize that most of the additional code in the OS kernel itself is security-related, go back and run Windows XP SP1 for awhile, and then install SP2 (you'll notice considerable performance differences). Microsoft has made considerable effort to strip Windows of all it's unnecessary interdependencies (
minwin), and making the codebase smaller and more efficient - however, portability is still a design goal of the OS, so it'll never be "thrifty" due to what I mentioned before (time and cost).
Again, why bother paying for 8 CPUs and 4+GB of RAM if it's going unused? Even tablets and phones nowadays are multiple-CPU devices with 1+GB of RAM, mostly because doing such is getting to be cheap at scale.