Only the Eclipse SDK comes in a 64-bit flavor for Windows. One solution is to install the Eclipse SDK, and manually install the plugins for Web, XML and Java development.

What I did is install the Eclipse IDE for Java Developer (32-bit), and copy the content of the Eclipse SDK (64-bit) over it.

In order to ensure the Aptana Studio plugin works on a 64-bit version of Eclipse, do the following ¹⁾:

• Make sure that a JAVA_HOME environment variable is set on your system.
  • To check or add a new environment variable, search for environment in the Start menu search box, and select Edit environment variables for your account.
  • If it does not already exists, add a user variable called JAVA_HOME, pointing to JRE or JDK on your drive, e.g. C:\Program Files\Java\jdk1.6.0_16 or C:\Program Files\Java\jre6
• Make sure the location of the JRE (or JDK) bin directory is your path by adding ;%JAVA_HOME%\bin to the PATH user environment variable. Create a new PATH variable if it does not already exists.
• Download XulRunner for Windows x64.
• Create a xulrunner directory in your Eclipse installation directory (e.g. C:\eclipse), extract the content of the XulRunner archive in this directory.
• Add the following at the end the eclipse.ini file located in your Eclipse installation directory:

-Dorg.eclipse.swt.browser.XULRunnerPath=xulrunner

• Install the Aptana Plugin using the standard instructions.