Excel can be used to get data from an OLE or DDE source (DCS, ethernet device, etc) and save it as a web page. A Macro can be set up to update values (calculate) and save as HTML...
OPC is based on Microsoft COM/DCOM technology, so you can use your OPC DLL as using other DLL in your website if your website supports COM/DCOM. And I think it will be easier to use MS ASP (Active Service Page) than use other Web technology (jsp, php, cgi, etc.) for your purpose.
