I lost count of the announcements, but as PDC draws to a close, here's a quick look at the big picture. How is Windows changing? And believe me, there are radical changes.

The one we will notice most is XAML, the new way to design a user interface. XAML applications use DirectX, so for the first time your high-powered graphics card will make a difference for ordinary applications, rather than just games. We will seet the same type of creativity that drives Flash applications on the Web, where no two buttons are alike. New 3D controls will alter the look-and-feel of Windows.

This is the reason for the Expression suite. Microsoft isn't really gunning for Macromedia, but simply providing what's necessary to design for XAML. Flash evokes mixed reactions on the Web, and we'll see a similar response to XAML applications. A bad XAML UI will be much, much worse than a bad Windows UI today, but the good ones should more than make up. Building desktop applications will need design skills, similar to what is needed today for web applications.

It isn't actually XAML, but the new Office 12 interface confirms the trend. We've had WIMP (Windows, Icons, Menus, Pointer) since the eighties. Now we just have WIP.

The rest of what's new is plumbing stuff, exciting to geeks but invisible to the rest of us. It is substantial though - XML messaging everywhere, .NET maturing as a replacement Windows API, WinFS merging database and file system. All this comes on top of the existing APIs, so bloat is a risk. There's also a ton of security stuff.  The biggest one is that in Vista, running Windows with limited permissions will be the default, as it always has been in Unix. Hope for a secure Windows? Well, the bad guys wormed into Windows XP with ease, though at the time it was meant to be secure, so I won't hold my breath. Give Microsoft credit though - it is making the effort.