So what else could we have hoped to see in Vista? Smaller, nope. Faster, nope. New features, yup, got that. But what's the biggie, what's the one thing that all those smug Mac users and incomprehensible Unix weirdos go on about?

Security. There's no way around it. Windows is a security nightmare. The reason we all get thousands of spams, the reason that we have to run virus and anti-spyware checkers that slow our high-power electricity-guzzling scalding-hot PCs down to the speed of the ones they replaced, the reason that the whole Internet is bogged down with sending all those spams, the reason that criminals hold websites to ransom for millions of dollars a year: it is all Windows' fault.

It's because of the hundreds of millions of compromised PCs that form zombie armies, sending spams, participating in distributed-denial-of-service attacks and so on, all without their owners' knowledge. They still work, they're just a bit slower. Who notices? Next year, you just buy a faster one. (With Vista on it.)
...
Another of the big holes in Windows is Internet Explorer. IE itself is not a bad browser, but the way it's been implemented and used is problematic. It's not only the web browser, it's also used to render a lot of the user interface. Secondly, Microsoft's model for dynamic content, ActiveX, is a security nightmare. The way ActiveX works is to download a normal Windows executable program - in geekspeak, a "native binary" - from the remote server, and then run it on the local machine with full local privileges. In other words, the stuff that you download from the Internet effectively becomes part of your installation of Windows, even if only temporarily. This sort of thing makes vandals' and security crackers' faces light up with delight and fills security consultants with the screaming heebie-jeebies.

So what could be done about this? How could Microsoft have fixed this in Vista if it wanted?

Firstly, the business of local accounts with full admin access. This is criminally stupid. No other serious multi-user OS works this way. There is a Right Way to do this, which everyone else does. (Well, all right, apart from a few heretics like Linspire and Puppy Linux, where you normally log in as root - but all the Linux pros regard those with creeping horror.)
...
So much for the user account thing. The other big hole in Windows is Internet Explorer. IE7 is an improvement. It's got a lot of beneficial changes: things like tabs and RSS support make it more powerful and usable and things like the built-in phishing protection are a step in the right direction.

But the big problems with IE are still there. For one, ActiveX. It was a bad idea in 1995 and it's a worse one now. No other browser works this way. The Mozilla family is derived from Netscape, which has its own plugin system and uses relatively safe, "sandboxed" environments for running interactive content, such as Flash and Java.
...
Microsoft's defence was that IE wasn't a standalone product, it was part of the OS, a component of Windows. (Although Windows 95 didn't actually come with it originally - and neither did any older version of Windows. And that you could install Windows without it, or remove it from Windows once it was installed.)

Right after this, Microsoft integrated IE deeply into Windows 98. The new and improved "Active Desktop" in Win98 was driven by IE: Explorer window contents were generated in HTML which was rendered by the core DLLs of IE, as were JPEG images.
...
For one, any exploits or vulnerabilities in the web browser automatically become vulnerabilities of the whole machine when that browser is part of the OS and always running. If the baddies can somehow sneak a dodgy file onto your computer, then even if you're disconnected from the Internet, if you open that file, your box is owned; the vulnerability is always present. You can't really firewall a computer from itself.
...
The web browser ought to be a separate subsystem with no connection to the machine's own user interface, freeing it to be large and clever. The local file browser should be simple, fast and responsive. There's no need to turn the view of the local filesystem into HTML, then pass that HTML through the web browser. Yes, it makes it easier to have fancy, customisable views with task-specific bars down the side and so on, but this is an inefficient way of doing it.
[right on!]
...
In an ideal world, I'd like to see IE completely replaced. There are enough HTML rendering engines out there - Mozilla's Gecko, KDE's Webkit, as used in Apple's Safari browser, Opera's code and so on. No need to use an open-source one - just buy Opera or hire the developer of the Apple browser iCab, say. There were too many bad decisions made in the course of IE's development, some of them motivated by commercial concerns like the Netscape lawsuit, rather than technical considerations - which should rule such a sensitive, critical piece of software.

Yes, getting rid of IE would break some websites, but then, IE7 does that anyway, and IE8 will doubtless break more. It would be a price worth paying.