SkinStudio does not officially support Vista (that is until the next version comes out). My suggestion would be to download a windowblind and check out the vista items in it. A good one to look at would be PixelPirates Adrenaline
WWW Link which has a Vista Substyle. In it you will see a section called 'Unsupported' with contains all the elements and images used for Vista. From there you can copy/paste the code needed (under the code tab) for each part. Other then that I don't really know what else you can do.