For 37 years now, Microsoft has built software for other companies’ devices. With the Surface tablet, which starts at $499, it finally designed a PC of its own — one of the sleekest, most ambitious devices ever to run Windows. The magnesium case looks and feels good and the integrated kickstand is beautifully done. And the super-thin magnetic keyboard cover — included with the $599 Surface, or $119.99 on its own — is way better than on-screen typing. There’s one big catch: Windows RT, Surface’s operating system, needs far more applications before it’s ready to compete with the iPad. But the device itself is so slick that it leaves you rooting for RT to take off.