>>>Windows progress bar? The worst time estimate I ever saw. Starts with five minutes, drops to 2 minutes after five seconds, then drops to 30 seconds after a minute, then shows 10 seconds for five minutes.
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>>>I need a progress indicator, not a bar named "Progress"... sounds so soc-realism, you know :).
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>>I think I used the wrong term. It is exactly what Windows shows when you copy a big file.
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>No, no, you were clear and your term is correct - that's what you meant. The trouble is in the windows progress bar, which makes wild mistakes when it estimates the time needed to copy anything that's not coming from a local disk and going to another local disk. When copying from a slow CD, or over a network - it mostly misbehaves in the manner I described.
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>So it's just like any other bar (now I'm using the term "bar" in any sense you may imagine) - you can name it "Progress" all you want, it's still just a waterhole for alcoholics. Or in case of Windows, a mockery. I still haven't seen it get much better than it was ten years ago.
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>And, BTW, the intended user is my boss - who shares my opinion about the Windows progress bar. We need something to tell him when to return to that machine and unzip the file. Doesn't have to look nice at all.

I don't think you would be able to do a precize prediction, because too many external factors are involved. However, you may try to gather some statistics, by measuring speed of copying different files in different time of the day with various PC load at the moment. Then you can use an average time, which may be only 10% close to the truth in each particular case...