A good chunk of my business is hardware/software related. I had a bunch of people who would call looking for free advice. As a previous poster mentioned, you end up losing 20 or 30 minutes easily..
What you also lose is your train of thought. ..
I just had 'one of those calls' yesterday. A guy who ends up averaging about 1 or 2 hours billable time at most.
My answer was "Sorry but I'd have to see the problem. I can come out this afternoon".. Of course, he was just looking for the freebee
Now, I do have one client/friend where advice is quid pro quo. I don't mind taking some time with him because he's done a hell of a lot for me over the years and continues to do so.