If you've upgraded to Windows 8, or bought a Windows 8 computer that doesn't have a touchscreen, you're missing out on much of the fun. The modern, tiled interface has been designed for touchscreens and, although it can still be navigated with a traditional mouse and keyboard, it's something of a chore. See also: Microsoft Windows 8 review
Logitech's answer is the T650 Touchpad. It's a large slab that's around four times bigger than the average laptop touchpad, and supports up to four-fingered gestures.
It supports all the standard Windows 8 gestures, so you can swipe in from the right to bring up the Charms bar, from the left to switch between open (modern) apps, and from the top to display the app bar.
You can also use two fingers to scroll up and down or left and right, and it's possible (using the SetPoint software) to choose whether the screen scrolls in the same direction as the movement of your fingers, or the opposite way. If you're trying to get as close to a touchscreen experience as possible, it makes sense to enable the option for moving in the same direction (it's disabled by default).
Two fingers can also zoom and rotate in apps which support those gestures. Using three fingers to swipe upwards takes you to the new Windows Start screen, and swiping downwards with three digits shows the traditional desktop.
Swiping left or right with three fingers takes you to the previous or next page respectively in programs such as Internet Explorer. Tapping with three fingers is the equivalent of clicking the middle mouse button.
Pressing anywhere but the bottom-right corner is a left click (pressing bottom right, as you might expect, is a right-click).
Using four fingers to swipe up or down maximises and minimises the Window currently in focus, while swiping left or right with four fingers snaps the window to the left or right side of the current monitor (a feature first introduced in Windows 7).
The T650's glass surface is very slightly angled, but feels parallel to the desk and very smooth in use. It connects to your PC or laptop via a proprietary dongle rather than Bluetooth, and can support other compatible Logitech mice and keyboards without requiring extra dongles.
During our tests, the Touchpad was very responsive for normal Windows use and the battery didn't need charging - Logitech claims it needs only one charge per month.
For Windows 8-specific gestures it was also very good. In fact, our main complaint was that pinching to zoom was very hit and miss - you have to be very careful not to rest your palm or any other unused fingers on the touchpad.
Even when concentrating hard, zooming was still fairly unresponsive and, unlike a real touchscreen, you still have to move the cursor to centre the point on which you want to zoom.
Similarly, it's not as easy to scroll on a map, say, as on a touchscreen. Moving your finger moves the mouse pointer, not the map. To scroll a map, you have to press hard (invoking a left-click) and then drag your finger over the Touchpad. Alternatively, you can double-tap and quickly swipe your finger to scroll around the map (if you're not quick, the map zooms into the next level). However, when you reach the edge you have the move the pointer back across the screen and repeat the process - not nearly as efficient as a touchscreen.
Naturally, it's the same story for clicking and dragging in any application, whether it's selecting text in Word, drawing a marquee in Photoshop or dragging and dropping files between windows. For these tasks, it's advisable to have a traditional mouse on hand.