Outlook Users
Here are some tips for making the switch from Microsoft Outlook® to Google Apps. 
Switching from Microsoft Outlook®
Life After Microsoft Outlook®

Quickly learn to accomplish some of the same tasks in Gmail that you're used to doing in Outlook.

Print this guide out and keep it handy as you begin using Gmail.
 Import your data Import your mail, contacts, calendars, and notes from your old Exchange profile or PST file.
What's not available in Gmail  See features you might be used to in Outlook mail  that aren't in Gmail.
Switching form Microsoft Outlook®: Gmail and Calendar

Self-paced training (short clips - 1 hour total) A comprehensive introduction to switching from Microsoft Outlook® to Google Apps. Covers threaded email conversations, contacts, labels, mail filters, calendar events, syncing events from Outlook, and more.