When you create your setup project, consider placing the image folder someplace that is 'known', such as c:\ProgramData\YogeshApp\img\ (for Vista and Windows 7). Then you can hard code the path.
The code below will take you to your 'known' folder on XP/Vista/7. Use the same notation for installations.
string imagesFolder = Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData) + "\\YogeshApp\\img\\";