To publish your database, you will need either FileMaker Server or Server Advanced. If you use a custom web publishing method - such as XML/XSLT, PHP or Lasso - then you only need Server. If you wish to use Instant Web Publishing instead, then you'd need Server Advanced.
You may also want to consider using a 3rd party hosting provider, such as ourselves:
Than you for the hosting offer but this is an internal 'intranet' application. My goal is to reduce the surface area of the application as well the expense involved. If I continue with the advancements requested in this application and upgrade it from Version 6 I'll need the server and at least 12 to 15 users. My goal here is try an reduce the expense of having to purchase up o 15 workstation 'copies/licenses' if I FMPro advance server (or server) will create the web application which the users simply access via URL.
I've been wanting to rewrite this application using a SQL server and ASP.NET but that would take far more time than simply making a simple change to the system.
In that case, you need FileMaker Server or Server Advanced as described above. Note that you can test Instant Web Publishing capabilities using a plain copy of FileMaker Pro. And if you join the FileMaker Technical Network for $99/year, you get a development version of FileMaker Server Advanced that you can try Custom Web Publishing methods with (PHP, Lasso or XML/XSLT).