Do you want to:

1. share information between colleagues
2. have documents stored locally and available everywhere
3. have your calendar available everywhere
4. share these documents with others
5. share calendars with colleagues
6. share addressbooks with colleagues
7. have your calender and documents available on your mobile
8. have no need to maintain and configure complex (Windows) servers
9. reduce costs
10. have your information securely stored on the web

Go for Google apps!