It’s the enternal question: Who’s less trustworthy — computer repair shops or used car dealers? If my experience in the last week with a local repair shop is any indication, computer repair shops lose, hands down.

Here’s the story. My daughter had a problem with her laptop. It would refuse to start, or would start and then crash after an hour or two…and then sometimes would work for five or more hours at a time before crashing. Then, after a while, it began flashing a message that the hard disk was about to crash.

My 16-year-old son said that he’d repair it for me. But I, Big Daddy, said no, I’d instead bring it to a repair shop. Big mistake.

I brought it to a place here in Cambridge. I won’t give the name, but for anyone who lives in the city, it’s the place out near Fresh Pond Parkway, near the natural foods store. I explained the problem to someone behind the desk. He said it sounded as if it were a problem with the hard disk.

Considering that’s the error message that would flash, I told him that’s a good guess. But I wanted the whole laptop checked out, just in case it was something else.

Did I want the data backed up from the hard disk? he asked.

Sure, I told him…until he told me the price — $300! That is not a misprint. He wanted to charge $300 to backup up 20 GB of data from a functioning hard disk. Right then, I should have left the shop, but I didn’t. Of course, though, I told him not to back up the data; I’d do it myself.

“Was the PC running slowly?” he asked.

Well, does the sun rise in the East? Don’t all PCs run slowly — isn’t that the nature of the beast?

Ah, he said. For $225 (or it might have been $250, I can’t recall), he’d give the PC some kind of virtual “bath” which would clean out any spyware or other unnecessary software. Obviously, I declined, considering that anyone could do the same thing using free or low-cost anti-spyware.

So if I had listened to him, he would have charged me from $525 to $550 to perform all of about a half hour of work.

For whatever odd reason, I didn’t run out of the store. Instead, I had them look at the PC, which they said would cost $65. That cost would be deducted from any work they did for me.

A few days later they called back. The laptop needed a new hard disk. (What a surprise!). They could buy one for $200, and would then charge from about $300 to $400 in addition to that to install it and Windows. So that means they would charge between $500 and $600 for replacing a hard disk!

Obviously, I told them no. My son backed up the data, got a hard disk for about $80, popped out the old disk, popped in the new one, installed Windows, drivers, and everything else my daughter needed, and put the data onto the new disk.

If I had taken the advice of the repair shop, the tab would have been up to between $1100 to $1200 to back up data, check for spyware, and install a hard disk. For $200 to $300 less than that, I just bought a whole new Core Duo laptop with 1 GB of RAM, separate graphics processor with 256 MB of RAM, and 15-inch screen.

So based on that, you tell me — who would you trust more, a used car dealer or a PC repair shop?