Confidential info on hard drive...'puter needs fixing...

How does one go about getting their computer checked out and possibly repaired when there is a lot of personal/confidential information stored on the hard drive?

My last computer crashed last fall, it won't start up...it stays in the "sleep" mode. I would really like it repaired if its nothing major (maybe the power supply?)but I've put it off because of all the confidential info I have stored. Am I just at the mercy of the repair technician, that they won't look at my stored documents? The IT guy at my work offered to take a look at it, but I just don't want anyone seeing my "stuff", whether it be him or a computer repair center. Not that they even would open up some of the documents, but just knowing they can makes me uneasy of course. My taxes are on there along with every last detail of our finances for college FAFSA applications, etc. I know there are some places that will come to your home, but I can't afford that.

Anyone have any advice?

Thanks~

Sandy