The following system requirements cover the SQL Server 2005 Express Edition:

Processor

32-bit Processor of 600-megahertz (MHz) or faster

Operating System

Windows XP with Service Pack 2 or later

Windows 2000 Professional with SP4

Windows 2000 Server with Service Pack 4 or later

Windows Server 2003 Standard, or Enterprise SP1

Windows Server 2003 Web Edition SP1

Windows Small Business Server 2003 with SP1

Vista Home Basic and above

Framework

.NET Framework 2.0

Memory

512 megabytes (MB) or more recommended

Hard Disk

Approximately 425 MB of available hard-disk space