SQL Server Express is now available with 10 GB Storage support. Earlier it was supported only 4GB. Now most SOHO users can use Microsoft SQL Express for their applications. It is ideal for websites and web based applications. It is coming along with a SQL management tool, reporting capabilities, full-text search, and spatial support. Compatible with all editions of SQL Server 2008 is the main advantage, once the size reach to 10 GB you can upgrade to normal version of MS SQL 2008 ( all editions ) . SQL Server 2008 Express includes both 32-bit and 64-bit versions. SQLEXPR32_x86 is a smaller package that can be used to install SQL Server 2008 Express onto only 32-bit operating systems. SQLEXPR_x86 is the same product but supports installation onto both 32-bit and 64-bit operating systems
Download and install Microsoft .Net Framework 3.5 SP1. And Windows Installer 4.5. before installing SQL Express 2008
Download Link : SQL Express 2008