For supported versions of Windows, along with disk and RAM requirements, see System Configurations.
AMD 64
The JDK for Windows AMD 64 comes bundled as an executable file jdk-1_5_0_<version>-windows-amd64.exe. To install this version, double-click this icon. For other details, follow the 32-bit Windows installation. Beta 1 has no update, patching, plugin or webstart support.