Short PHP script to show advertising based on country

Hi there, I have (probably 2 quick and easy) tasks: 1.) I would like to link to different destinations depending on visitor country. Picture and text of the ad can be the same but link is different. For example: The website shows an amazon product picture. if the user clicks on the picture (or text) it leads the user to [login to view URL] if the user comes from the United States but if the user comes (e.g.) from the UK it leads to the product page of amazon.co.uk. 2.) I would like to show different pictures and links to visitors. For example: Visitors from the United States see amazon iPhone ad and visitor from United States sees amazon Blackberry ad. As far as I know it should be possible with php as a server side solution. I am using wordpress for my website with the following theme: http://headwaythemes.com. Usually I can easily add a php widget to the sidebar. Being able to do it quick and inexpensive is a plus! Best regards, Chris