Over the last decade or so Microsoft has had an interesting series of Operating System releases, and established a trend of hits and misses.
Don't believe me? Well tell any techie you know you've got a problem with your computer running Windows Me and watch their face, that look of pure unadulterated horror will explain everything. Windows Me is widely considered in tech circles to be the bastard child of Satan and a pit viper and is regarded with about as much warmth as Bill Gates at a Linux convention.
Windows Me took everything about Windows 98, a decent enough O/S in its own right, and tried to marry it with Windows 2000, the resulting horror was just ugg. Don't get me wrong, every now and then you'll come across someone running Windows Me that just loves it, they some how managed to get the "just right" combination of luck and hardware to let the beast run smoothly, but that's about as rare as an honest politician.
After Windows Me came Windows XP, XP was a quantum leap in O/S', it was fast, elegant, and stable, that isn't to say it didn't come with problems, it did; the disaster of the first time activation was there.
It did away with the legacy of Windows 9x and moved onto Windows 2000 solid server style base and made itself the desktop of choice for a hell of a lot of people. Windows XP is still one of the best O/S' out there, powerful and stable, pretty much everything anyone wants.
Now lets jump forward to Windows Vista, now personally I think it gets a slightly over hyped rep for being crappy, but it did throw away a lot of things Windows XP worked hard to overcome, XP removed the stigma of the BSOD (Blue Screen of Death), since it became very rare, and the need to reboot every 30 god-damn seconds that was common in Windows 9x machines. Vista took that hard won ground and did a Olympic level sprint back over it to lay a turd.
Oh sure Vista's stablity wasn't as bad as say Windows Me, but damn, it was a step down from XP, and it was a resource hog, actually saying that is unfair to hogs, Vista sucked every available resource it could, from hard drive space to RAM to CPU time, it was all your resources are belong to us Microsoft style, over time a lot of the issues in Windows Vista were fixed by patches and service packs, but Vista never recovered from the opening rounds of "oh my god this sucks"
Now we get to the meat, Windows 7 RC (that is not the final version ffs) is a better O/S then Vista after three years of extra work from launch, a machine running Vista that struggles and chugs will run Windows 7 without blinking, its got all the stability of XP, all the pretties of Vista, and its still not the final version!
I've heard it called "What Vista should've been" and I agree totally, while I only made the jump after my Vista install died a horrible death and I wasn't willing to head down to Portland to find my DVD, I don't regret it at all, it's an exceptional operating system. I recommend to anyone running XP or Vista to upgrade to Windows 7 as soon as the final release hits stores soon.