This is always an interesting position to be in.
I could always do with the extra cash from sorting out these machines, but I have to rate my time carefully. I know what places like Dial-a-Nerd costs, and I can't charge that, bit nor can I do it for free.
I had one parent once ask me to fix them up. I went around to their house, did work, scoped the machines out to give advice, and even phoned and faxed around to get info for her. That's when the problems started, she couldn't afford my measly R250, the excuses came thick and fast. Yet her kids are at my work, a place where you pay through your nose in fees. The whole situation turned acrimonious, and in the end I wrote it off as a bad debt. I've also never taken on parent's jobs again.
I expect to get some business after the school hoildays now, when I explain to staff how infected their home computers are with the latest malware. Time will tell though
One thing that rings true though from earlier posts, is the drivers issue, and then the fact that few of them actually have a legal installation of Windows and Office. It's usually gotten from a "friend of a friend".
I'll probably need to get an external hard drive to image the drives before working on it. With malware, sometimes even after cleaning, your system is still just vrot.