I was able to get a surface with sharp corners by using a Manual Surface Extraction (B-Spline option) followed by a surface trim using a sketch.
This point cloud is not very dense, that is the reason there are all the "lumps and bumps" in the resultant surface.
You could probably get a much better result creating a boundary surface or loft surface manually. You can snap points of the construction curves (splines) to the mesh. If you use SW2008, you have better mesh snap options through the use of the Section View tool as well as the Curve Wizard.
Hope this helps.
Thanks for your reply.
The point cloud is imported from excel and will be around 10times more dense than the file I posted. I want to try and write amacro that will automatically create the surface once the pointcloud is imported so using boundary surfaces would not bepractical. One option that you mentioned that might work isover-sizing the surface then cutting it back down to size to ensuresquare edges. The square edges are required as I am then offsettinga rectangle of the same size and extruding up to the surface tocreate a solid, which will then be sent to a milling machine viasolid CAM.