Hi Praveen,
1. You will have to uninstall PCo before installing the OPC Core Components, then re-install PCo.
2. Which OPC Server are you attempting to connect to Remotely? The OPC Server Vendor (Kepware, MatrikonOPC, Rockwell, Siemens, etc.) should provide a document that describes the required DCOM settings for the client and server PC. If one is not available, this one from Kepware is a good reference:
http://www.kepware.com/Support_Center/SupportDocuments/KTSM00010_Dcom_Configuration.pdf
DCOM security is usually implemented by the site IT group, as it is a network security ownership issue with many companies.
3. What is the version/patch level of MII that you are wanting to connect the destination to?
Regards, Steve