Time and Expense - basic db design

Taking the requirements from my previous post I set about to put together a simple database structure that would serve as the backend for my prototype T&E application. Below I have indicated to what extent the functionality is supported by the proposed structure:

- Timesheet entry
      primary functionality
- Client / project / job management (both billable and non-billable)
      project/work item management is primary functionality
      client management is not part of this app
- Staff management including the ability to analyse planned staff availability and setup schedule of rates
      not part of this app
- Expense management
      primary functionality
- Decent reporting / charting / analysis / modelling functionality
      support provided through reporting services
- Ability to export into csv, xml etc
      support provided through reporting services
- Invoicing / billing management
      not part of this app
- Email notifications (timesheets due, upcoming staff availability, billing/invoicing due etc)
      not part of this app (initially)
- Be able to track Time and Expenses OFFLINE
      primary functionality
- Be able to integrate with TFS
      primary functionality

See the following image for an overview of the initial database which should cater for most of these requirements.  I say initial because like most projects, I'm sure I will want to change the scope as I go along.....