Need count of unique text values in column

I need a formula that counts all the clients that are assigned to Hannah (only 2 in this scenario). Since this document is a list of all individual purchases, there are duplicates. I can count the unique clients with the following formula:
=SUMPRODUCT((B2:B10<>"")/COUNTIF(B2:B10,B2:B10&""))
... but I need it to look up and count only the clients which belong to Hannah.

Help?

	A	B	C
1	Account Manager	Client Name	Purchased Item
2	Hannah	Jerry	7008
3	Mark	George	9980
4	Hannah	Jerry	9980
5	Mark	Sara	1367
6	Mark	Leo	9980
7	Hannah	Deb	1367
8	Mark	Leo	2045
9	Hannah	Jerry	2045
10	Samantha	Paul	1367

Try this:
=SUMPRODUCT((A2:A10="Hannah")/COUNTIF(B2:B10,B2:B10&""))

or perhaps:
=SUMPRODUCT(($A$2:$A$10=A2)*($B$2:$B$10<>"")/COUNTIF($B$2:$B$10,$B$2:$B$10&""))

Please click the Add Reputation star below any helpful posts, and if you have your answer, mark your thread as SOLVED (Thread Tools up top). Thanks!-Lee