Oracle to SQL connection

http://www.databasejournal.com/features/oracle/article.php/10893_3442661_1

1) Create DSN
2) change $ORACLE_HOME/hs/admin/inithsodbc.
3) Change listner.ora as per D:\oracle\product\10.1.0\db_1\hs\admin
4) change tnsname.ora as per D:\oracle\product\10.1.0\db_1\hs\admin
5) Now Start Listner ( Create Database link using SQL server User / Pass )