Desktop Communicator

I am looking for someone to build me a desktop application. It will work like this: I run a successful chain of self replicating marketing websites which my members subscribe to. I need a desktop communication system built so that I can run all communications such as new opt-in notifications, new & announcements from us etc to be delivered DIRECT to the desktop of the person that downloads our application. A member will download our desktop notification application and install it. Once they install it, the application will ask for their username and password. That will tell the system who they are and that information comes from my already existing MYSQL database. I will need an application for every different website we have out there but will start with just one. All the messages that are sent through the desktop notification system will be stored in our database where the messages can be retrieved if the member was offline at the time we sent the message. Please let me know if you require additional information.