Just to be clear, the '2 weeks' is a made up number. I know it will run a very long time but there is no real way to tell how long without actually running the query.

1) Yes you can run an Estimated Execution Plan on the query without actually running the query. Since I don't know your SQL Server version, I can't tell you exactly how. In general, in the Management Console, where you can run the query, there should be an option under VIEW for Estimated Execution Plan. (I don't have SQL Server 2008 but can check 2005 and 2000). It would have to be a table space scan since there is no Index on Field1.

2) As rmiao stated, the transaction log should only record transactions (Insert, Update, Delete). A Select would have no reason to write to the transaction log. If it was increasing in size while your other query was running, something else must have been causing it.

3) I don't know enough about SQL Server to know how the NO LOCK and the 10 million row insert will react with each other (I am mainly a DB2 DBA with some knowledge about SQL Server).

I am not sure what you mean by "... it is being served as product by one of the external vendors.". How is it being used?

Would it be possible to create a multi-column table and create a view that concatenates the columns to replicate what the current table looks like?

PS If nothing else, try an index on Field1. This might at least give you an index scan. Since more keys can fit on a page then data rows, there will be fewer pages read. If you can add all the rows being used by the query to the index (with FIELD1 first), you can get an Index only access and not have to read Index and data pages. (Or you can make the index on FIELD1 a Clustering Index.) Both of these should reduce the elapsed time but I can't begin to tell you how much.

PPS How long does it take to Insert 10 million rows? Are rows ever deleted from the table or will it continue to grow by 50 million rows per week (assuming a 5 day week)? If nothing is deleted, whatever bad performance you currently have will just continue to get worse.