query performance -- revised!

Apologies for the last post (query performance) -- especially because I made the mistake before. I have corrected my syntax and there is still a threshold (43 ORs) at which it switches from using an index to using a table scan on the Address table. I am suspicious of its decision because our previous db server (OpenBase) ran this query considerably faster, even with hundreds of ORs. Query and query plan:

SELECT /*+ INDEX(Address address_postalCode) */ count(pr.board_certification)
FROM Practitioner pr, AddressXPerson axp, Address a, OrganizationXPerson oxp, Pe
rson T1, Specialty s
where ((a.postalCode = '07010'
OR a.postalCode = '07020'
OR a.postalCode = '07022'
...
OR a.postalCode = '10007'
)
AND (oxp.role = 'Practitioner' AND axp.role = 'Location' AND a.country = 'USA' A
ND s.englishDescription = 'Urology' AND pr.remove_from_mdlocator <> 1)) AND T1.p
ersonOID = axp.personOID AND axp.addressOID = a.addressOID AND T1.personOID = ox
p.personOID AND pr.personOID = T1.personOID AND pr.specialtyOID = s.specialtyOID
;

Execution Plan

   0 SELECT STATEMENT Optimizer=CHOOSE (Cost=170 Card=1 Bytes=74)    1 0 SORT (AGGREGATE)

   2    1     NESTED LOOPS (Cost=170 Card=1 Bytes=74)
   3    2       NESTED LOOPS (Cost=167 Card=1 Bytes=57)
   4    3         NESTED LOOPS (Cost=166 Card=1 Bytes=41)
   5    4           NESTED LOOPS (Cost=163 Card=3 Bytes=93)
   6    5             NESTED LOOPS (Cost=160 Card=3 Bytes=81)
   7    6               INLIST ITERATOR
   8    7                 TABLE ACCESS (BY INDEX ROWID) OF 'ADDRESS' (
          Cost=154 Card=3 Bytes=39)

   9    8                   INDEX (RANGE SCAN) OF 'ADDRESS_POSTALCODE'


           (NON-UNIQUE) (Cost=2 Card=3)


  10    6               TABLE ACCESS (BY INDEX ROWID) OF 'ADDRESSXPERS
          ON' (Cost=2 Card=18844 Bytes=263816)

  11   10                 INDEX (RANGE SCAN) OF 'ADDRESSXPERSON_ADDRES
          SOID' (NON-UNIQUE) (Cost=1 Card=18844)

  12    5             INDEX (UNIQUE SCAN) OF 'PERSON_PK' (UNIQUE) (Cos
          t=1 Card=287899 Bytes=1151596)

  13    4           TABLE ACCESS (BY INDEX ROWID) OF 'PRACTITIONER' (C
          ost=1 Card=86492 Bytes=864920)

  14   13             INDEX (UNIQUE SCAN) OF 'PRACTITIONER_PK' (UNIQUE
          )

  15    3         TABLE ACCESS (BY INDEX ROWID) OF 'SPECIALTY' (Cost=1
           Card=1 Bytes=16)

  16   15           INDEX (UNIQUE SCAN) OF 'SPECIALTY_PK' (UNIQUE)
  17    2       TABLE ACCESS (BY INDEX ROWID) OF 'ORGANIZATIONXPERSON'


           (Cost=3 Card=26009 Bytes=442153)


  18   17         INDEX (RANGE SCAN) OF 'ORGANIZATIONXPERSON_PERSON' (
          NON-UNIQUE) (Cost=2 Card=26009)