I've never heard of an "ipg" format. Are you sure it isn't "jpg"? If it is, all that has happened is that Windows thinks the files should be opened by Photoshop, but as it has been uninstalled, it can't find the program. Try opening the pictures with Microsoft Paint, or even Internet Explorer (go to the file->open menu and click browse). If that is the problem, you can go to the tools->folder options menu when you open My Computer, and click on the file types tab. From here just find the file type, and click change to change the program the file will be opened with.
Hope this helps.
goates