Back in the day, before the personal computer revolution, techies would speak of the relationship between two machines as "master and slave." The master was the remote mainframe in the climate-controlled room, with all the power and the smarts and the software that could actually do something. The slave was the "dumb" terminal on the worker’s desk, incapable of much of anything on its own. What that structure – and terminology – said about organisational structure and values did not go unnoticed.

The invention of the personal computer was, explicitly, a rebellion against this power dynamic, one that would put the technology in the hands of the people. No need to call on central services (the IT department) anymore, or to subordinate your needs to those of an all-powerful master; everything you might want, computing-wise, was now sitting on your desk, under your own control.

The internet, paradoxically, is shifting this power dynamic once again: Google's announcement last week of a web-based spreadsheet application is just the latest example of the speed at which computing is moving off the desktop and onto the server farm. Microsoft Office is in some ways the last bastion of the PC-era model, the one piece of application software that you pretty much have to have living on your own machine. Its days may be numbered.

From a technical standpoint, the logic of the intelligent network, as opposed to the intelligent desktop, is pretty obvious. Google's massive clusters of machines can bring far more computing power to bear on a problem than a single user ever could. There are large economies of scale in data storage. Security and support are much easier to handle centrally. And on and on.

Even more importantly, so much of computing these days is about communication and connection that the very idea of the standalone PC seems quaint. The power of the internet lies precisely in its ability to tie the desktop into a much larger and richer world of data and applications. If you're finding what you're looking for through Google, and using Google Maps, Google Images and the free Google e-mail, well, why not use Google for word processing and spreadsheets too?

Yet I think it's worth considering whether there's risk in shifting all the power off the desktop and onto the network – in effect rendering our PCs "slaves" once again, with Google or Yahoo! or Interactive Corp (or any other provider of online applications) in the role of master.

On one level, many new internet services give at least the appearance of user control, and allow a far greater degree of individual customisation and privacy protection than any mainframe ever did. At the same time, a lot of this control is illusory: it's true that you can refuse to accept cookies – files that internet sites install on your PC in order to track who you are and what you do – but a lot of sites won't work at all if you don't accept them. Similarly, privacy policies and terms of service are often highly unreasonable, but again the choice is agree or forgo the service entirely.

Personally, I'm not comfortable with Gmail, because I don't like the idea of Google reading my mail. Google says it only machine-reads the email in order to display relevant advertising, but still, it gives me the creeps. For similar reasons I would not want to store all my data on a Google server (such an offering is rumored to be in the works) because, well, it just makes me uneasy to have my data under someone else's control. This is probably a little irrational – even sitting on my own hard drive that data is at the mercy of my hardware, and it would arguably be more secure somewhere else – but that's how I feel.

The Powerbook G4 sitting on my lap is anything but a dumb terminal. And yet, the majority of what I do with it – visiting and interacting with websites – could be done with far less horsepower. While I've never thought of Microsoft as the champion of the erstwhile slave in the face of the all-powerful master, maybe I'll have to think again. Office is terribly overpriced, but the next time I open Excel I'll be thinking of it in a whole new light.

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