Requirements:
Size in its compressed downloadable form: 1.2MB (fits on a floppy!)
Consumes only 2.5MB of drive space
Requires the .NET Framework
Operating System: Supported on Windows2000 and Windows XP
Requires Microsoft Internet Explorer--5.5 or later
What can and do you get?
Downloadable at http://www.asp.net/webmatrix/default.aspx?tabindex=4&tabid=46
MSDE (Microsoft Data Engine) -- free runtime version of Microsoft SQL Server
Will allow you to build dynamic, data-driven applications
Microsoft Mobile Internet Toolkit
WYSIWYG Web form designer
Set of tutorials
.NET Framework ClassBrowser designed specifically for Web Matrix
Links to the active ASP.NET community