All-in-ones are interesting little (or in some cases, big) PCs. They're desktops with integrated displays and are often built with laptop-grade parts. As such they've inherited a bad reputation for poor performance compared to their full-on desktop tower brethren. The stigma is not completely undeserved. Mobile graphics cards and processors have always lagged behind those made for personal computers.However, the all-in-one form factor has its own advantages. These self-contained PCs take up less room than a giant full-size tower and don't create a giant tangle of USB and display cables. What's more, some all-in-one computers are doubling as giant tablets. When's the last time you were able to pick up your PC and screen off your work desk and ferry it over to work on the couch?Without further ado, here are the best all-in-ones we've reviewed.Dell XPS 18An 18-inch tablet-PC you can take on the goThe Dell XPS 18 blows away any notion that all-in-ones are hulking great machines tied to desks.