I think alot of the responders on here missed the boat. Regardless of whether or not this person has asked a myriad of situaltional questions regarding business ethics, you have no idea whether or not this person is actually performing unethical services.
The fact that the person posting the questions may be from someone that is lookign for other techs to give advice. Perhaps he or she has been working on computers for years, but is lacking when it comes to business ethics. That is not something we should discourage here. I thought this forum was used to help and guide new and existing IT techs in the right direction, especially when it comes to the repair business. By provinding professional and ethical responses and advice. I have not seen this here regarding the responses this person's questions.
From what I have read, the poster has posted pc repair business questions, and it is not our place to tell him how he wants to run his business, but only to offer our experience to help them move in teh right direction.
Now to answer his question:
There is no law that says you cannot perform work on the side, providing the same services as that of the company that employs you.
However, should your employer find out, I am sure they will scrutinize your work and find a way to fire you...usually by reason of inefficiency.
Also, in my opinion, it would be ethically wrong for your to solicit your services during your work hours, or to provide any reprieve for the customer in trying to get a better deal by having you fix their computer.
and finally, if you want to provide pc repair services, then my advice is to start your own business using the advice and experience that is being offered by this site. Always remember, if you are unsure that what you are doing is not kosher, then it probably isn't and you should go with your gut.