The above result can be obtained in Inkscape if you follow this tutorial. It certainly takes a lot of patience to use the Bezier tool to draw around the figure to trace the silhouette from the picture, but once you are comfortable with it, it will come to you as second nature. I would recommend using a tablet for more control than a mouse. I use a Wacom Intuos 3. Lets start!

For this tutorial, I used a picture from SXC.hu. You can get it from the following link http://www.sxc.hu/photo/347110

 
For this tutorial, I will assume that you know the basics for Inkscape and are familiar with your way around the software. We will use the Bezier tool to draw the outline of the above picture into something that looks like the shape on the right. You have for most details you have to zoom in by using the + key often during the whole process. Once you are done with the shape, we can then move on to tweaking it.

 
The traced bezier shape above can be selected with the "select and transform objects" tool by pressing F1 and then clicking on the bezier path. Give the path the following stroke and fill settings, a flat colour fill of value 800000ff and a stroke paint value of 000000ff with the stroke width at 1 px.