That's a taken considering you only need Tomcat to run JSP pages. So if you are using PHP then you are not using Tomcat. As for MS-IIS, that's Microsofts web server software. IIS is the equivelent to Apache, but for running on windows. Personally I'd be on linux and apache rather than windows and IIS. I think the LAMP format is more stable and faster performance. Also, I'm a skin flint Scot and can't be having with paying for liciences if I don't need to.I've decided to use PHP 4.1.1 and MySql to develop my site running on Tomcat using Microsoft-IIS/6.0, the latter details being meaningless to me as i haven't a clue what that does or doesn't mea
The database engine will handle may concurrent requrest. The system would only have a problem if you were using Access for the database. But any proper SQL is designed to handle such a enviroment. You will have to program against concurrent edits (two users altering the same record at the same time, one overwrites the other) but no concurrent selects (readers).
As for scalling, mysql can be clustered if needed. The server aps you name can all be scalled as required.