Aside from your basic business plan that only you have knowledge of...I think that it is a good idea. Box houses like Circuit City and Best Buy offer that service now. Give them a call and get their rates as a comparison. I know some older folks would like that service especially if it was cheaper than the big companies. Setting up printers and software for people could be helpful.
I would think you would consider the cost of fuel (trip charge?) and a minimun service call rate. Good Luck.