That would all depend on how you do things and the steps you take to overcome things. No the links will not remain the same and there are things you would need to do to correct things which would involve work on your part. Example being you could do the import and then once things are fine remove vbgallery directory and take steps to rename and run photopost under the existing directory name. Thus say you link images like so which a url like this
http://www.domain.com/gallery/showim...atid=newimages
Well then you could do like a mass mysql replacement query on the
vb post table to say replace showimage.php?i with showphoto.php?photo and then the photo links would work and if the linking is different than this there would be some more tedious things involved so it all depends what your doing as yes switching programs old links are always broken.