I am new to server side development and my experience is limited to some fairly simple PHP to execute and display an SQL query. My experience is mostly Delphi and C#. Basically I am able to program the required functionality in Visual Studio C#, but need to build this as a server side web app.

Cross platform (linux) would be an advantage although all development work would be in Windows as i'm more comfortable with it.

I would like opinions and comments regarding development environments and tools for feature rich web pages with database access too. Also access to a native DLL may be required to write data from the page to a serial port device (Custom device).

Options seem to be:

PHP
ASP.Net / Silverlight (cross platform?)
Java / Javascript
Eclipse? (I downloaded this but don't really know what it does!)

Any comments or advice much appreciated.

Regards,

Matt