The default options for downloading Microsoft’s SQL Server 2008 Express at www.microsoft.com/express/Database/ will have you downloading the application through the Web Platform Installer. This is suitable for installing on a local computer, but if you want to install it on multiple machines, especially those that do not have an Internet connection, its best to do it with a standalone version of the installer.
There are no direct links on the download page to get the installer, but you can find it at:
http://www.microsoft.com/downloads/details.aspx?FamilyId=7522A683-4CB2-454E-B908-E805E9BD4E28&displaylang=en
There is a 32 and 64-bit version and you may need to download other applications in order to install the database server, i.e. .NET Framework 3.5 SP1, Windows Installer 4.5, and PowerShell 1.0. There is also an option for download documentation for offline viewing.
