470159 Custom desktop and/or browser app

We have 4 twitter accounts that we are looking to create an app either to be installed on a PC or into a browser (firefox, IE) where its only purpose is to 1) notify when we post tweets on the users computer 2) stream our feeds into a viewer so they can read our tweets without logging into twitter or other app. It is strictly for our userbase. we do not need any customization on the users part. THey install it and every time we tweet, they get notified and a copy of the tweet appears in the app. I know there are apps and plug-ins for websites to do this, but I am looking for an installable custom branded app for our company