(MONEY Magazine) – If you are one of the 34.7 million Americans who has a home office, chances are you depend on your PC. And if you're loath to let the computer leave your desk--even when it breaks down--your best move may be to have a repair technician make a house call. The convenience of home repair is obvious, but the potential pitfalls--say, bad work for too much money--may be less apparent. We canvassed the pros on how to hire a computer doc who will do the job right, at the right price.

The Yellow Pages bristle with small, independent operators, and it's up to you to figure out who's best--or even competent. Whereas a local technically adept college student may suffice to coach you through software glitches, registering an e-mail account or learning to surf the Internet, a malfunctioning machine probably requires the attention of a professional.

A qualified on-site technician can help with anything from translating incompatible files to salvaging crashed hardware. Before you hand over your beloved hard drive, though, check references and credentials. "At least half our business comes from referrals, and that builds up trust," explains Chris Akin of PCFixx in Seattle.

Popularity aside, the technician that you choose should have A+ certification, which is awarded by the nonprofit Computing Technology Industry Association after candidates pass a written test. In addition, make sure the technician has been recently certified by your computer's manufacturer.

Charges range, on average, from $75 to $95 an hour. To prevent any nasty surprises, ask about fees for travel time, and request an estimate (some repair services charge for estimates, so ask about that too) and a time frame for completing the repairs--especially if the technician has to order parts.

You think you've found a great bargain? Well, think again. "If you're paying much less than $75 an hour, it could mean that the technician lacks experience," cautions Joseph Cotrona of Computer Application Techniques in New Rochelle, N.Y.

--Jennifer E. Keeney