SQL Server data extract with limited performance impact

Question

Background:

I have a SQL Server 2008 Enterprise Edition database containing three tables. The tables contain ~3 million, ~14 million, ~14.5 million rows respectively.

Problem:

I need to do a data extract from the database for reporting purposes. This will involved joining the three tables and writing each row to a text file. This database is currently taking production traffic and I want to limit performance impact. This data extract should not prevent reads, writes, or updates from occuring during the course of the process.

From the research I have done, I believe adding the 'NOLOCK' hint to the data extract query will allow the production traffic to behave normally while still accomplishing my primary task of the data extract. I'm assuming the dirty reads associated with the 'NOLOCK' hint will be isolated to the data extract query.

Am I correct to assume that the 'NOLOCK' hint on the data extract query will only affect that one particular query? Does it affect all queries being executed on the database while the data extract query is executing?

Is there a better approach to accomplishing my goal than what I've presented above?