There is an article in Oracle's knowledgebase called "metalink". Have your oracle dba log into metalink and look up docID 191368.1 entitled "How to create a sql Server linked server with the oracle provider for OLE DB". This article is very specific about how the OLE provider options are to be set. For example, you are to go to the options of the Oracle provider within SQL server and check the boxes "Dynamic Parameters" and "Allow InProcess".

Another thing to remember with Oracle client on the 64-bit box -- is that you will need both the 32-bit and 64-bit clients installed because a 32-bit app will need the 32-bit client and a 64-bit app will need the 64-bit client. And finally, the default install of a 10g client does not include the OLE provider. You have to go back, do a custom install and make sure to check the boxes for the OLE client services.

Hope this helps you solve your problem.