Web hosted database app

I require a web browser app with a front-end UI and back-end database; either MySQL or SQL Server 2005/2008. Front-end UI: I want a web page that allows a new user to create a unique username and password and have it stored in the back-end db, checking for user already exists on submit, and asking for a new name. I want a login page that on success, allows two-tier heirechal use of the main app; Admin (Full access) and User (Restricted access) to subsequent pages on the site. The user must be validated to be unique on login and this uniqueID used to keep track of subsequent use of the app. e.g.: access to pages that access records in the db. I want a main web page (following successful login) with db SQL routines for insert, update, delete of records and make/copy tables included, to use as a template so I can create other pages for the rest of the site as needed. The graphical design of the webpage needs creating. Back-end DB: The DB will be either MySQL or SQL Server. It has to handle upto 1,000 concurrent users with scaleability to 5,000 concurrent users. Db access needs to have record locking while under edit and full robust error trapping and reporting to the user. Compatibility: Must run in I.E => v7 and Firefox. Overview: I am designing the Db structure right now and can generate the pages that will make up the main app myself once I have the Add new user, User login, User validate and Main pages along with a page that carries the sample SQL routines listed above. Project deliverables: Add New User web page User login web page Login validate web page Main web page (to land from after login) SQL samples page Testing: I will test these pages on my own laptop, running under IIS 6, against the db I am designing.