To quote the immortal Robert Heinlein, "There ain't no such thing as a free lunch."
When I was a poor, underemployed, single lass, I always at least offered friends a homecooked meal and a fun evening (watching movies, playing cards, etc.) if I had to ask them for help with my computer or whatever else. Fortunately I'm a pretty decent cook (if I do say so myself) and it got to the point where I'd get calls like, "Hey, I just replaced my CD/rom drive with a faster one; want me to come over and install my old one in your machine? And, um, could you make that alfredo thing again?"
I may not have had the money to pay friends for their professional services, but I wouldn't dream of leaving them uncompensated. An evening of babysitting, an offer to cater their next party, a couple homemade frozen lasagnas for those busy evenings, lovely home-baked goodies for their next office potluck... I always offered, even if they refused, because both my pride and their free time were on the line.
My old dentist even asked me if I could "pay" him in cheesecakes a few times, but that's another story...