Then I moved to the US, haven't heard the guy in a year, then out of the blew he finds me on msn, messaging me with a problem he has,...
haha, oh dear.
i know what you mean about whether it's something i'd be able to enjoy. i would consider it as a 'job' and not a hobby so i wouldn't be expecting it to be too much 'fun'. i worked in a school for a while as an IT technician and found it pretty dull. the people were great, it was nice to help them out but the boredom came from having to sit around and pretend you were busy when you waiting for the next problem. i imagine being self employed wouldn't be so dull as i'd be able to crack on with other stuff during the slack periods.
i could easily live with charging people for the service i'd provide - i can provide a more personalised service than a shop so that has to count for something AND the point of charging is so that you don't end up with 'friends' like you described above. no point resenting someone pestering you if you've made it clear to them that you are their free personal assistant, but if you make it clear there is a fair charge to be made and they don't wish to pay it then it's time for the them to find another sucker.
my only real issues are not whether to charge but how much to charge. i can price myself lower than the local pc shops but i'll not be dealing with as many customers as them so unfortunately i need to charge more to make it worth while. so, the service i provide has to be better than the competition - which might equate to spending more time helping the customer or just providing a better quality or faster service.
hard to say really with all this - i guess i've just got to do a trial run and learn as i go along rather than theorise about it all.