Ajax Messenger

We need someone to create a simple IM messenger. 1. When a user login to the site, he will see his friends online and when the user click on his/her friend username, a pop up window will open up where they can chat with each other. 2. We need a simple light chat where all the members of a group can chat with each other. Only members can chat and nobody else can chat there. However, members can still IM each other through that window if they want. 3. If a user leave a offline message, next time a user login to the site, he shud see the messages on his messenger box. 4. User can send file to each other if they want.