I wanted to celebrate Bill Gates's departure by reminding myself of what life was like when windows were things that let the light in, writes Lucy Kellaway.

I AM writing this column with a silver fountain pen. I had planned to bang it out on a manual typewriter, but I threw away my old Olivetti a long time ago and don't know anyone who still has one.

Pen or Olivetti makes no difference: the point is not to write it on a computer. I have just started a 24-hour low-tech vigil to mark the stepping down of Bill Gates, who more than any other human being has made the modern office what it is.

I wanted to celebrate his departure from full-time work at Microsoft by reminding myself of what life was like when windows were things that let the light in.

Last Tuesday afternoon, I composed an automatic e-mail reply that said: "Lucy Kellaway is in the office, but not on the computer. You can send me a letter, or ring, or visit me on the second floor." Then I pressed Submit, but got a message saying: "Error. Database has too many unique field names. Ask administrator to compact database." God, I hate computers.

I love them, too. I have no truck with the idea that they have frazzled our minds and shrunk our souls: most office workers seem to be doing perfectly well, as far as I can judge.

Although I am addicted to e-mail, it's quite under control. Twenty-four hours' cold turkey would be no problem. "I bet you £2 you'll crack," my daughter said when I told her about my plan. "Done," I said.

That afternoon, I shut down my machine and turned off my BlackBerry. I cleared enough space on my desk for a lined pad of paper. I sat and looked at it.

What am I supposed to do now, I wondered? Research my column, was the answer. But, without the internet, how does one find anything out? I became a journalist in the year 15 BPC (Before Personal Computers) and so I should remember, but I can't.

Then I noticed that lots of people seemed to be coughing and squeaking on their chairs. Computers, it seems, make one deaf and, with the computer off, it was as if the power of hearing had returned to me.

This wasn't entirely a pleasure as the sounds of an open-plan office are better blotted out, especially if you are trying to concentrate.

Otherwise, though, I was finding concentrating fine. The problem was that, deprived of all the stimulation of the internet, I wasn't sure what I was supposed to be concentrating on. I looked longingly over a colleague's shoulder and saw that he was reading something on the BBC website and writing an e-mail. His screen was busy; I just had a blank sheet of paper. That evening, I went home early, feeling anxious about all the people who were surely trying to get in touch with me.

At around 9pm, I snuck upstairs and quickly checked my e-mail, reasoning that, as I was at home, it didn't count. This was a mistake: not only was there nothing interesting but also my daughter caught me at it and so I lost face . . . and £2.

The next day, I got in late, there being no hurry. The black screen on my computer looked like a death, but what had died was my job. I felt an impostor in the office, feebly jotting down some notes on a pad like a work experience person.

I didn't want to disturb colleagues as they were attached to screens, so must be working. I stared out of the window, fretting that my lunch might have been cancelled without my knowing. In fact it wasn't, and I made it a long one and had some wine in the way we did in the BPC age.

Back in the office, feeling slightly tight, I wrote a thank you letter to my lunch host. An e-mail would have taken about one minute, but a traditional letter was quite a kerfuffle, involving a hunt for envelopes and paper and two phone calls, one to directory enquiries for the company phone number and one to the company for the address.

It took me 11 minutes all together, but I felt an unfamiliar stab of satisfaction when I was done and put the crisp envelope into the almost disused out-box.

Then I settled down with the fountain pen to write this. It was the biggest shock of all: writing with a pen involves thinking about what you want to say. On the computer, there is no need for this: I write any old thing in vast quantities, hoping that eventually I will write something I quite like. On a computer, I write, then think.

But the fountain pen forces one to do it the other way round, which is quicker but much harder. I am woefully out of practice.

But how many words had I done? How did we live without word count? I reread what I'd written and it seemed a bit amateurish, as if this was my first article ever. Still, a little earlier than usual, I was nearly done.

It had been a peaceful, if slightly lonely day. My phone had gone twice, both times the IT help desk trying to sort out the out-of-office e-mail problem from the day before.

One person dropped by for a chat. I received no letters.

I had set out to see what work would be like without a computer. This, I discovered, was the wrong question. Work IS computers now.

The two are the same thing. It may be technically possible to work without them, but one has the feeling that one is in a wrong age or a wrong key.

Computers may make it hard to concentrate and they waste acres of time. But I don't want to go back to the quieter life BPC.

I want to turn my computer on, copytype this article, check the word length, then see if anyone exciting has sent me a message. - (Financial Times service)