Does this make sense?

[ZenGum]

So, I'm looking at getting a new computer system.

I was bemused, bewildered and baffled by the large numbers of different processors about and the lack of any means to compare them. What I need, I thought, was some way of testing all processors against some standard test, and comparing that.
Oh, internet, so full of nerds, and google, how I love thee. www.cpubenchmarks.org has the lot, and very well presented.

This site scores processors over eight tests, producing a number currently anywhere between a few hundred and 10,000. Higher is better. I call these units "bangs", as in bang for your buck.

So, I started with my old machine, an Intel pentium M at 1.73GHz. It produces a modest 448 bangs, apparently. It was fine when it was new, but now is slow, buggy, and has other issues. The HDD is effectively full. It is about 4.5 years old.

So, reasoning that computers double in capacity every 18 months, and I've had this computer 4.5 years, I need to multiply every thing by 8 to get an up-to-date equivalent.

Right?

So, I need to go from 448 bangs to about 3584.
I should go from 504 MB of RAM (What? I was sure I had got a gig! can a half a gig ram chip burn out without being obvious?) to 4 GB.
I should go from 60 GB HDD to 500GB.

There are processors in the correct bang range (3300-3800) at reasonable prices:
AMD Phenom II X4 820 (3517 bangs, $100)
AMD Athlon II X4 645 (3567 bangs, $110)
Intel Core i3 530 @ 2.93 GHz (3551 bangs, $125)

These options seem to be available on the market to me now.

The only thing I'm concerned about is that maybe these statistics just don't support the kind of reasoning I am doing. I've never seen these sorts of numbers before. So, does anyone want to save me from my own clever-stoopit? For example, I don't understand how altering the RAM would effect the bang measurement. Do I need to octuple both the processor bang and the ram? or is just say, quadrupling the bang and doubling the RAM enough to create the eight-fold increase in performance I want?

And also, is windows seven tolerable? Most new machines seem to come with it, but XP is still about.