Access & MS SQL databases vs. My SQL and PHP vs. ASP & .NET

Hello,

I have a question regarding the use of different databases on the Internet.  I have the Microsoft Hosting 1&1 MS Developer at www.1and1.com.  I can change to Linux Hosting 1&1 Developer at any time.

My website is being designed to have a blawg which will apparently be the first of its kind in the legal field and could potentially get nearly 30,000 attorneys looking at it per month and/or subscribing to the RSS feeds, and/or any other way I can get the information available to attorneys (podcasts, vcasts, etc.), including easy access for disabled attorneys.

Updates to the blawg will vary each month, but could occur, on average, 12-20 times per month.

I desire to use databases to also keep track of newsletter signups, two other blawgs (with nowhere near the potential popularity as the abovementioned idea), a multi-part forum, online payments, online responses and potentially other database needs.

The Microsoft Hosting 1&1 MS Developer supports Access databases and allows for two (2) MS SQL Databases (maximum capacity = 200 MB each MS SQL Database) and a 1&1 WebDatabase.  This package also supports ASP, ASP.net 2.0 and the .NET Framework.  Lastly, apparently, ASP.NET cannot be used in conjunction with MS Access Databases.

The Linux Hosting 1&1 Developer allows for a 1&1 WebDatabase and up to 100 MySQL databases (maximum capacity = 100 MB each MySQL database).  This package supports Perl, Python, PHP3, PHP4, PHP5, and Cron Jobs/Scheduled Tasks and includes a Perl Syntax Checker.

I am developing this website using Macromedia Studio 8 and am familiar with Access databases and own Office 2007 Ultimate, but I am unfamiliar with the SQL databases (both MS and MySQL).  I am somewhat familiar with ASP and VB Script, but can easily take the time to learn other scripting languages as well.

What I need to decide is what databases to use on my website.  This will help me determine which of the above packages to use at www.1and.1.com.

For the database needs mentioned above, what database types would be best?  

What would be the least expensive solution to set up and maintain?  Easiest/quickest to program?  Best free or low-cost solutions found online?

All suggestions, comments and questions are welcomed and appreciated.

Thanks,
edsager