Microsoft & Oracle - Need help!!

Have anyone of come across this scenario..
I am working to configure a solution whereby An application already developed in Microsoft technologies (3 tier architecture web based - with Microsoft ASP, VB objects and SQL server Database)needs to have an application level connectivity with an Oracle database. For specfic business needs the data entered and retrieved through ASP application and VB objects must link with Oracle database server without connecting to SQL server database. Privacy & security mechanism must be in place whereby data that is specific to Oracle must go through the Oracle server without ( at any cost!) linking to or flowing through the SQL server database.
Could someone help me some suggestions?