I quote a fixed price for a straight format and reload of windows, then if they want more programs adding back in and their data, it's half as much again. The format/reload takes place on my bench at home. I explain that it will take 3-6 hours depending on the updates downloaded. For 90% of the time I am not working on the computer - it is doing things and I come back and check it from time to time.

If I deliver it back to them and they ask me to hook it up to whatever, it's a straight per hour basis.

For example, I got round to one guy who wanted it hooked up to his wireless router, no problem - then I found that he wanted a printer hooked up as well (no problem either), then he wanted his email set up, another profile and the list grew longer and longer.

Then he said - are you done yet? I need to go!!!!

I just billed him for more labour than the hardware was worth... and he paid without a problem.

After all, if you take your car to a mechanic, you expect a fixed price for a particular service and you pay extra for the bits and pieces you want done as well. If the mechanic finds something they phone and tell you how much it's going to cost on top of the fixed price. If the garage has always served you well in the past, you are quite likely to just authorise the work and pay up.