Online heads up poker is a very hard field to get into, although I do know several players who play the $50-100 stakes and win a good percentage of the time. They are not your average gamblers though; they have strict routines and probably tilt 1/100 games if they are having an incredibly bad streak!
That is the key anyway, take it match by match, but overall you need to be hitting somewhere between a 58-60% win rate to be profitable overall, and have the bankroll to take your downswings in online heads up poker. Do not think that 100 games is a good enough sample either, I'd be looking at around 500-1000 games before you will see a clear indication of where your game is with online heads up poker, mainly due to the variation of results.
Playing online heads up poker is slightly different to offline, mainly due to the fact that you can't see the opponents face. If you give off your emotions fairly easily, then this is definitely a good thing, as they can't see your face either.