I often find myself wanting to know when certain friends from my Xbox Live friend list log on, but when I'm currently not playing something on the 360. I mostly stick to the official XBL page that lists all friends and messages, but not only is the site incredibly slow loading, but I hate having to refresh the page constantly to see if someone logged in or not.

A friend told me that he thinks there is a program or toolbar that will notify PC users in realtime when somebody logs in, or when a message is sent. Does such a thing exist, and if so where can I download it?