Behavior of conditions with null left outer join

[aamkumar]

I am using a left outer join in a select statement as

select CR.MKTG_CD_ID, CC.Name_ID, CC.Name, VCR.DOB

from CC

INNER JOIN VCR on VCR.CONTACT_ID=CC.CONTACT_ID

LEFT OUTER JOIN CNTC_MKTG_RESP 	CR on
CR.CNTC_GROUP_ID=VCR.CNTC_GROUP_ID 
and CR.MKTG_CD_ID<> 8248

WHERE CONDITIONS.....

In this above case I get records for CR.MKTG_CD_ID<>8248 including null value records, but I am also getting record where CR.MKTG_CD_ID=8248 ( Actually it should be removed from the record output )as Null value in CR.MKTG_CD_ID column for that record.

BUT if I define the condition as

LEFT OUTER JOIN CNTC_MKTG_RESP 	CR on
CR.CNTC_GROUP_ID=VCR.CNTC_GROUP_ID 

where (CR.MKTG_CD_ID is null or CR.MKTG_CD_ID<> 8248)

I get all the records for which CR.MKTG_CD_ID<>8248, Null value records for CR.MKTG_CD_ID and the records are not repeated with NULL/Blank value where CR.MKTG_CD_ID=8248

I am not sure why it is giving me this behavior is SQL SERVER 2000

Please advise