ViBook supports up to a 23-inch monitor at 1680x1050 or 1600x1200 resolution. Like the ViDock, it renders graphics on the device itself, offloading the processing from your on-board graphics card. This is good, because it allows you to attach four (for Macs) or six (for PCs) more monitors to your setup. But it's also bad because it relies on the rendering power of the device to display windows, so there's no OpenGL or any kind of real acceleration.
It's best used for extending your desktop so you can keep your mail, or your RSS feeds, or your IM windows or your calendar visible at all times. Not so much if you need to do anything graphics-based, or anything that refreshes really fast. No games, especially.