You've no control on which data file table is allocated, only filegroup. You'll have to create another filegroup and use ALTER TABLE..MOVE TO to relocate the table (if table has clustered index). If table doesn't have clustered index, you can create one on new filegroup and delete it after table has been moved. See http://www.mssqltips.com/tip.asp?tip=1112 for more info.

>I have a db with a 280GB data file. It has a table with 185GB. I want to create a 2nd data file and put that table into it.
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>creating the 2nd data file seems straight forward. I have not been able to find the best way to move the table into the 2nd data file. Does the 2nd data file need to be in a 2ndary filegroup, or can they both be in the primary file group. I do not find anything in the table properties that tells which data file it is in, only which file group it is in.
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>Your help is greatly appreciated.
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>P.S. - this is a MOSS (SharePoint) database, so I can not go in and create (or re-create) a clustered index on the table.