Yes. Assuming you don't also sync to Outlook on your desktop, you need to:
Originally Posted by qpid360
1) Backup the contacts/calendar info on the device (You'll nedd a third party utility for this. Most of the utilities here: http://pocketpccentral.net/smartphon...are/backup.htm offer a free trial for x# days- certainly long enough for you to migrate to Google.)
2) Delete the mail2web partnership (erasing the contacts and calendar from your device)
3) Create a GMail account for contacts and calendar (Or, if you already use GMail, log into Google Calendar and/or GMail contacts and clean out any old info you don't want to sync with the device and to prevent duplicates.)
4) Restore your contacts/calendar on the device from the backup
5) Set up the new Activesync account with Google and sync.
Everything should be fine at this point. Now, for bonus points, you can try to find a sync tool to sync Google Calendar/Contacts with whatever PIM program you use on your PC (Outlook, Thunderbird, etc.) and have wireless syncing between the PC and the device.
Todd Allcock, Microsoft MVP: Mobile Devices 2007-2011