Shared To-Do List

[Betty]

Hoping someone can point me to some software that will work for us. Here's the situation:

I have 2 employees that share an office on seperate computers. They need to have a shared task list that works similar to MS Office - Outlook - Tasks in that it's not just a list, but has the ability to add notes to it.

It must be viewable and updateable from both computers.

Any ideas?