I've been converting bitmap images into vector graphics for about 10 years and in my experience there is no better way then doing it manually. Tracing programs should only be used when accuracy, quality and file size are not issues which is very rare.
You can spend hours playing with image contrast and trace settings and in the end you will have to edit the results. I skip all the messing around and do it manually 99% of the time because my work calls for quality and I can give an accurate quote of how long a job will take me.
If you don't have the time or the experience to convert an image please have a look at my online portfolio athttp://www.geocities.com/vectorcopies and then send me an email.