I solved this at my site by uploading objects of the image class to the (in your case) product class object itself (in other words using the product as parent for the images).
I then made template code for the full view of the product class fetching all children of image class, and displaying them inline with the product. This allows you to have everything from 0 to unlimited number of images.
To upload several images at once, I can recommend the multiplefileupload extension: http://www.ez.no/community/contribs/applications/multiplefileupload
