SQL Server 2000 and below do not support encryption nativly.
SQL Server 2005 is the first version to support encryption. The database it self is not encrypted. Data within the table is encrypted. There is no meta data which says that data within a specific column is encrypted. You can look in the sys.symmetric_keys and sys.asymmetric_keys to see if any encryption keys have been created. To see which data is encrypted you’ll need to look in the stored procedures which load and return the data to see if they are encrypting or decrypting the data.
If you have encrypted data and you don’t have any records in the key DMVs then either the encryption is being done by another method within the database, or it is being done by the UI before the data is inserted into the database.