Data Migration from Oracle to SQL Server If you need to do a data migration from an Oracle database to SQL server, what approaches and technical solutions are the best practice?

Our database has about 100 million rows and a total of 52 tables.
You can do this directly from SQL Server Management Studio. 
Within SSMS, just right click the database, select Tasks -> Import Data, select an Oracle typed data source and set up your connection to the Oracle database. 

Here's a really good description of the full procedure, including setting up an Oracle client on the machine doing the migration.

http://dbadiary.wordpress.com/2012/10/04/data-migration-from-oracle-to-sql-server-with-ssms/