a nolock on an update is ignored anyway, so there's no advantage to adding it anyway.
only SELECT statements will honor NOLOCK, and then you get the usual possibilities about doubled/repeated data, missing data, and data that is returned but doesn't exist any more.
help us help you! If you post a question, make sure you include a CREATE TABLE... statement and INSERT INTO... statement into that table to give the volunteers here representative data. with your description of the problem, we can provide a tested, verifiable solution to your question! asking the question the right way gets you a tested answer the fastest way possible!