MySQL Data directory move (WAMP)

I removed the old WAMPServer 2.0 and it left my old MySQL data directory and my.ini intact.
I installed the new WAMPServer 2.2 and need to make my old databases active with the new WAMPServer MySQL.

When I set the data directory in the new my.ini to point to the old data directory, I get this error when trying to start the service:

Could not start the wampmysqld service on Local Computer.
Error 1067: The process terminated unexpectedly.

No other errors. In the Application Event log I see this:

Fatal error: Can't open and lock privilege tables: Table 'mysql.host' doesn't exist

How do I get around this as the old MySQL version was 5.1.36 and the new one is 5.5.16.

You'll need to copy over ALL the contents of your old data dir to the new data dir. Specifically it sounds like you did not copy the mysql folder (read mysql database) over to the new data dir.

StackExchange Database Administrators Q#9922, answer score: 2