It just sounds like you have to register the files in the viewport.zip file.
The 'SmartSubclass.dll' & 'SmartViewport.ocx' files go in the same folder as a file called 'Regsvr32.exe'. (99% of the time it's the system32 folder, sometimes system on older machines). So if you have doubts where to put them, just look for Regsvr32.
Then open up the ms-dos prompt
(Start->Programs->Accessories-> Command Prompt?)
Then navigate to the folder where you put them.
Assuming yours is the same as mine, the commands you type at the prompt as soon as it opens are
>cd.. <enter> to get back to c:/
>cd windows <enter>
>cd system32 <enter> to get to the sys32 folder
>Regsvr32 SmartSubclass.dll <enter>
>Regsvr32 SmartViewport.ocx <enter>
the last 2 lines are what registers the files and you should get some confirmation. Hopefully I explained it okay