Requirement:

500 MHz or faster processor
256 MB RAM; 512 MB recommended for graphics features, Outlook Instant Search, and certain advanced functionality.
3.0 GB available disk space
1024x576 or higher resolution monitor
Windows XP (must have SP3) (32-bit), Windows 7, Windows Vista with Service Pack (SP) 1, Windows Server 2003 with SP2 and MSXML 6.0 (32-bit Office only), Windows Server 2008, or later 32- or 64-bit OS.
Size: 655 MB