Force.com IDE Installation

Install as Standalone Application

For users developing exclusively on the Force.com platform, these installers will download Eclipse code from a public mirror and configure the Force.com IDE to launch as a standalone application:

• Windows Installer (32-bit)
• Windows Installer (64-bit)
• Mac OS X Installer
• Linux Installer (32-bit)
• Linux Installer (64-bit)

Note: you may need to install the Java JRE on your system.

Install as Eclipse Plugin

If you are already an Eclipse user, these instructions show you how to install the Force.com IDE into your existing Eclipse distribution or upgrade from a previous version:

• Force.com IDE Installation for Eclipse 3.6
• Force.com IDE Installation for Eclipse 3.5
• Force.com IDE Installation for Eclipse 3.4
• Updating the Force.com IDE from a previous version

Source : http://wiki.developerforce.com/page/Force.com_IDE_Installation