Desktop Application for an Affiliate Website

We are a company that operates an affiliate website that gives cash back to its users for shopping on their favorite websites by first clicking through us. We are looking for a design of a desktop software application that will remain hidden on the user's computer, but will alert the user when he visits one of our partner websites. A small pop-up (similar to the windows update pop-ups in the bottom right-side corner) with a clickable link will emerge that alerts the user that they can get cash back by clicking the link and going through us. The browser window will then be redirected to the same website, but with our affiliate ID attached to the URL. We do not anticipate this to be a very complex project. All the software has to do is access a list of our partner sites online, and if the user's URL is pointing to one of them, the software must provide our affiliate link as a reminder pop-up at the bottom of the screen. Of course, the software must have all standard features of desktop apps such as turn off, uninstall, etc. The idea is to have the software available for installation on our website. If possible, we would like the software to work for both PC and MAC. We are not really sure what language would be best for programming this software, but we will leave that to your disgretion. Perfect functionality is all we require. A similar type of software is available on [login to view URL], who have a very similar business model to ours. We do not anticipate this project to cost more than $500.