... and for a bonus answer. Because of the XML data structures/schemas I deal with I can get away with the lazy guy technique of "*:". This is not a Best practice though. The best practice would be to declare and reference the namespace like so:

Using the sample data from my previous post...

WITH XMLNAMESPACES ('Com.Commerce.Data/PaymentData.xsd' AS NS)

SELECT *

FROM dbo.tblOrder

WHERE zPaymentData.exist('/NS:PaymentData/NS:CreditCardResult')=1;

OR (my preference when declaring namespaces)...

SELECT *

FROM dbo.tblOrder

WHERE zPaymentData.exist('declare namespace NS="Com.Commerce.Data/PaymentData.xsd"; /NS:PaymentData/NS:CreditCardResult')=1;