PALO ALTO, California -- The mobile work force is very real; the popular image of the mobile worker is not. If it were, companies would have to devote a huge portion of their technology budgets to removing sand from laptops.

At any given moment, roughly a third of our workers are not in their offices, but they're not at the beach, either. They're engaged in classes, conferences, customer visits, and team meetings at disparate locations

The key is making information as mobile as they are -- delivering it securely to mobile phones, pagers, PDAs, laptops and, often overlooked in discussions of mobility, stationary systems.

Imagine being able to insert your personal identification card into a Simple desktop -- really just a monitor, mouse, and keyboard -- and having your personal workspace instantly appear. That's what I do every day, not just in my own office at Sun Microsystems, but in any of our San Francisco Bay Area locations.

As I move around, I know the connection and all the data is encrypted and secure. Plus, the device is so simple (no operating system, no local storage) it can't collect viruses or loose critical data -- yet the user interface is just as advanced as any PC's and just as easy to use.

Later this year, my roaming area will expand to include the rest of North America, Europe and Asia.

Travel happens to be a big part of my job, so I'm thrilled about having the ability to travel light and still have access to all my personal files and productivity tools -- exactly as I left them the last time I removed my smart card.

This type of mobility shatters the old economics of personal computing. Suddenly businesses no longer need a microprocessor for each employee. Usinglow-cost desktop appliances powered by servers in the back room, we're able to operate at 25 users per microprocessor, doing some pretty heavy-duty workloads -- and saving millions of dollars on electricity alone.

With such appliances, the only reason you'd ever replace the hardware is if it breaks. Software upgrades (and hardware upgrades for that matter) are all handled the easy way - on a centralized server. That also means that a single administrator can manage as many as 2000 desktops -- unheard of in the PC world.

Now think about another kind of mobility, a kind that has been with us forever: the need to move an employee from one office to another. Customers I've talked to say such moves cost them anywhere from $800 to $1500 each. We have employees who change offices practically every day and it costs us nothing.

Moving is as easy as sliding a smart card out of one machine and into another, so people can easily reorganize themselves into new teams – and for a large, dynamic company, that can add up to millions of dollars a year in savings.

With this approach, we've also discovered that the company no longer needs to supply an office for every employee. In sales, for example, we average 1.8 users per office, since reps tend to be out on sales calls much of the time.

Though the ratio may vary, the same principle applies to most groups in the company, so we've set up "flexible zones," where some offices are available on a first-come, first served basis and others can be reserved the way you would a conference room. Yet every person's personal digital workspace meets up with them wherever they go.

When you really stop and think about it, the best place for data is not on a desktop or a laptop but on the network, just as the best place for money is not in your home but in a bank. It's safer there, and more accessible – all you need is your bank card.