Today, your choice of operating system is a critical one; for tomorrow's computer it won't matter nearly as much.

In five or ten years, your choice of operating systems could become as mix-and-match as the choice of web browsers, as rapidly improving virtualization technology allows you to run multiple operating systems (OSs) simultaneously on one computer as "virtual machines," each with its own selection of programs.

One key factor driving that trend will be hardware innovations that make existing virtualization run smoother and faster. AMD and Intel are shipping CPUs with hardware support for virtualization. Apple's adoption of Intel CPUs points the way to a multi-OS future as well, and the company's BootCamp software permits dual-booting into Windows. Parallels virtualization software lets Macs simultaneously run Windows (and other OSs), much as VMWare and Xen do under Windows and Linux. One day, virtualization could free us to run any app in any OS, at any time.

3D interfaces are also predicted to become commonplace as PC graphics improve. Early third-party 3D desktops like those listed at NooFace could become a standard, productivity-boosting OS feature, especially if coupled with new file systems.

And next-generation file systems could finally shed the decades-old directory tree storage structure and act more like databases, said analyst Tony Iams, who covers operating systems for Ideas International. Windows Vista's WinFS file system may have died but its ideas, such as network searches, live on.

The web hard drive will arrive as online storage gets cheaper and more plentiful every day. In a few years an OS will be able to interact seamlessly with the troves of online storage spread around the web.

And website YouOS.com hints at the promise of a fully online desktop, as do the growing number of everyday online programs that run within a browser and require no installation. The ability to go from work to home, or notebook to desktop, and look at the same online layout for all your programs and files may well prove very attractive.