What we recommend:

1. Install CP 4.1 to a new folder within the web tree and make it an application root.
2. Using Admin | Utilities move the data from your SQL database to the supplied CP 4.1 Access database.
3. Move the template and test the store.
4. Set the current store to maintenance.
5. Make a backup of the SQL DB
6. Repeat step 2 to get the latest data
7. Drop the SQL tables from the SQL database
8. Use the Admin | Utilities to move to SQL
9. Test
10. Rename the current stores folder as an archive.
11. Name the CP 4.1 installation to the current folders name.
12. Drop the application root for the CP 4.1 installation install.

If you have any questions, please let us know.