You can move the location of the Exchange 2007 storage groups and databases, even after installing exchange. But, the process has to be done out of hours as it will dismount the databases. You can use both the exchange management console and shell to achieve the same.
In order to move the storage group path, launch EMC. Navigate to Server Config -> Mailbox and right click the storage group and select “Move Storage Group Path”.
Browse to a location of your choice for logs & system files and click Move. It will prompt you to confirm that you are ok with dismounting all databases within that storage group. Click Yes and it will start moving the files.
Once it is completed, the databases will be mounted back automatically.
In order to move the database location, follow the same steps. Navigate to Server Config -> Mailbox and right click the mailbox database that you want to move and click “Move Database Path”.