I m trying to automate Excel thru C#.net, having vs2005 and Excel 2003. when i deployed the s/w in a different m/c. It throws me the following Error message.

"This operation failed because the QueryInterface call on the COM component for the interface with IID '{000208D5-0000-0000-C000-000000000046}' failed due to the following error: Library not registered. (Exception from HRESULT: 0x8002801D (TYPE_E_LIBNOTREGISTERED)). "

I have already tried to register by using
""C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\regasm.exe" Microsoft.Office.Interop.Excel.dll "
no luck

any help would be greatly appreciated.

Does it have the same version of excel installed?

Yes, Same Version of Excel is Installed.