or a sneak peek at the future of computing, go to YouOS and click "Try a Demo." Your browser window turns into a desktop of its own, with sub-windows for e-mail, chat, and Web browsing. There are also links on the YouOS desktop for a sticky-notes program and a rich-text editor. But these programs aren't on your hard drive—they're running somewhere in the vast unknown Internet.

YouOS is the fledgling startup of four recent college grads with a bit of angel funding. Its simplicity makes it a great demo. Anyone who logs on can instantly spot the big idea: You don't need Windows! You don't even need a PC! You can login and work from anywhere using any gadget with a screen and a keyboard.

Just because the demo and the name are cool doesn't mean YouOS will replace Windows. It does, however, serve as a proof-of-concept for people who doubt the viability of Web-based operating systems. Check out YouOS for 10 minutes, then imagine the same project on a billion-dollar budget. Now do you think the mythical Google PC that's allegedly being secretly developed in Silicon Valley—or in China or on a Ukrainian IRC channel—will become reality?