Compamy Intranet Job & Time Sheets

We are a small design company (12 people currently) who wish for an cheap intranet/internet online basis Job/Timesheet solution for monitoing hours on jobs. We have and host our own website, so it could reside here or on our workserver. It will need to let our employees enter their daily time into a data solution that can me monitored by Job, Time, Daily, weekly, Monthly and by Employee which can be accessed by a password protected administrator (me). Their is a mix of operating systems, mainly mac but some pc's too. An online diary would also be advantageous with each employees being able to add data of their own (colour coded for ease of use) but not able to alter anyone elses (this would be viable for the administrator, me). Also in the main header area just a simple area for short messages/information which again can be written by anyone but altered by the administrator.