With spreadsheets, documents, browsers and emails all on the go at once, many people end up cobbling together whatever ageing monitors they can find to give them more space in which to work. But once you’ve plugged in two TFTs, adding more is either a pain or simply impossible.

The answer, according to Asus, lies not in buying more graphics cards, but in sending the image via USB instead. Connect its EZlink-enabled VW223B to your PC using the provided USB cable, install the driver from the CD when prompted and it’s ready to go. An EZLink icon sits in the system tray, and with a quick click you can control the output to the monitor, from straightforward mirroring to extending the desktop.

We fired up DisplayMate to test the picture quality, and the results were good. The black level is deep, gradients are smooth, and with its 3000:1 dynamic contrast we could distinguish the final few shades at both ends of the scale. The 300cd/m2 brightness doesn’t result in perfect bright-white screens –there was a slight green tinge we couldn’t remove.

But EZLink’s real weakness is that USB has much lower bandwidth than DVI or VGA. Load up video or a 3D game and you’ll see why USB won’t be challenging DVI anytime soon. Even an older game such as Call of Duty 2 is rendered up to a second slower on the Asus than on a normal monitor. And when we tried to maximise the most basic low-resolution video clips, they stuttered to the point of being unwatchable.

So, it’s not suitable for any sort of entertainment, but in a multi-monitor setup that’s not an issue: just make sure you watch video on your main DVI monitor, and use the Asus for Outlook or web browsing. If you really want to go to town, you can daisy-chain up to six of the monitors from a single USB port on your PC.

The Asus VW223B isn’t for everyone, then, and we wouldn’t advise using it as a primary monitor, especially as it has only a VGA input to supplement the USB. But for anyone looking to extend their desktop without splashing out on a new graphics card, it’s an ingenious idea.