increasing database performance using indexes

Hi,

I'm trying to increase the performance of my database by using clustered and non clustered indexes, but the retrieval time seems to be high.  When only have clustered indexes on my 3 tables the retrieval time is 3 seconds, but when i add non clustered indexes the retrieval time is 6 seconds??

I have 3 tables.

ProperyType                                PropertyDetails                          Owner

TypeID (PK, clustered)                     DetailsID  (PK, clustered)               OwnerID (PK, Clustered)

PropertyType (non clustered)               TypeID (FK, Non clustered)               ForeName

                                           OwnerID (FK)                             SurName

And i use the following syntax to retrieve the data:

SELECT ow.ForeName, ow.Email, pr.Type
FROM dbo.Owners ow
INNER JOIN dbo.PropertyType pt ON pt.OwnerID = ow.OwnerID
INNER JOIN dbo.Properties pr ON pr.TypeID = pt.TypeID
WHERE pr.Type = 'Penthouse'

Can anybody offer any advice on to improve the performance and if my indexes are correct?  The most commonly used columns are the ones with non clustered indexes on them.