Depends on what profile you are wanting to use on your helical, and if you want a solid or a surface. So far, I have only found 1 routine that successfully extrudes a profile other than a circle along a helical path, with the end-product being a solid. It is written by Fuccaro at another Cad forum:
You have to follow the directions carefully as to how to use it.
The problem with all other spiral routines is that they twist your profile as it is extruded along the path.
Here are some examples of Fucarro's helical exrusions.
Off topic-he has some interesting routines he wrote for a telephone cord and a shell that is worth checking out.