See, OC is already something of an improvement over MS Paint visually. Now keep practicing!
I must admit, that freehand line tool in Xara looked useful. Photoshop has something similar, but it's way too sensitive and puts in too many control points for my liking (maybe it's an option i've not seen yet). The other feature I'd like is being able to change the width of the line along the length of the line, which I don't think is something Photoshop does. That Sai Tool thing that everyone seems to be raving about at the moment is supposed to offer features like that. If I had time, I'd have a look at the Sai demos.