I tried again.
Here's what I did:
NOTE: This is on a Pre2 - different device and software version (2.2.4).
1. The first time I deleted the google account, all google data on the device was transferred to the built in Palm account.
2. I opened the accounts app in 'System' and removed google.
3. I restarted the phone
4. I opened the calendar app, and from the top left drop down menu, I selected Preferences and Accounts.
5. From there I added google.
6. It took a little bit of grey spinning disk (1min?) before it went to the next screen. I selected what services I wanted to use from google (calendar, obviously) and clicked the green, 'Create' button.
7. This all went Ok, then there was a notification that the calendar was syncing (another minute?)
8. I now have everything back. Old stuff is now duplicated, but that's better than lost.
I hope that helps.