Without knowing more about your needs in terms of:


Permissions
Number of projects
Number of documents per project
Cross project/department integration
...


it's hard to give real good advise, but as a baseline my recommendations would be:


Create Site Collection per department to handle permissions and possible split into multiple content databases
Create Subsite per project if few/small
Create Site Collection per project if many/large


The setup of project sites can be streamlined, by having a common Site Template from which they are created

Department sites having multiple projects and different files
Starting four days ago, I wasn't able to open any of the icons at the bottom of the page of my MacBook. I downloaded Snow Leopard, and now I can open all but GarageBand. This is a complete mystery to me. 

I'm currently at OS X 10.6.3. (my Mac was bought used, do I need something newer to run Garageband?. How can I get GarageBand to run again? 
