Where do I click, again? A guide to Windows 8

The main thing to know is that Windows 8 is designed especially for touch-screen computers, to make desktops and laptops work more like tablets. It is Microsoft's way of addressing the popularity of tablets, namely the iPad. But Windows 8 will work with mouse and keyboard shortcuts, too. It'll take some getting used to, though.

There are two versions of Windows 8, or more precisely, there's Windows 8 and there's Windows RT. They look the same, but they run on different processing chips. Windows 8 runs on standard chips from Intel and AMD and is the version you'd get if you're upgrading your home desktop or notebook PC. Windows RT is the version for light, small tablets and laptop-tablet hybrids.

Windows 8 will run programs written for older versions of Windows. Windows RT won't. It's limited to applications specifically written for it and available through Microsoft's store. (As a consolation, a version of Microsoft Office is included free on Windows RT devices).

Here are some tips on how to navigate the new Windows:

— When you start a Windows 8 machine, you're greeted with a screen that shows the time and a pretty picture. To get past it with a touch-screen device, swipe upwards with your finger from the bottom edge of the screen. If you have a keyboard, hit any key.

— Next, you'll see a mosaic of Live Tiles, each representing an application. Programs specifically written for Windows 8 will run in this new environment, which is unofficially nicknamed Metro. Each application fills the screen when you run it. Applications written for older Windows versions will open up in something that looks very much like the old Windows Desktop environment. You can switch back and forth between Metro and the new Desktop, though Microsoft wants people to eventually use only Metro.

— The Desktop screen lacks a Start button, so it's hard to start programs from there. Microsoft's idea is that users should learn to go to the Metro tiles to start programs or access settings, even if many programs, including some Windows utilities, will open up in Desktop. To get back to the tiled Start screen with a mouse or touchpad, move the mouse cursor to the top right corner of the screen, then swipe it down to the "Start" icon that appears. If you have a touch screen, reveal the Start icon by swiping in from the right edge of the screen.

— In the Desktop environment, you can glance at the Taskbar to see which Desktop programs are running. If you're a mouse or touchpad user in Metro and want to see what's running, you have to know this trick: Move the cursor into the top left corner of the screen, then drag it down along the left edge of the screen. If you have a touch screen, swipe in from the left edge, then quickly swipe back in.