Ronnie, on his pale horse, asked me for help regarding JDK installations after he received the 1723 error. He, like the other horsemen of the apocalypse, also had a 64-bit Windows Vista/Windows 7.
There are two common types of Java packages: JRE and JDK.
JRE: Who needs it?. Computer users who run applets and applications written using Java technology
JREs are somewhat of a subset of the JDK and the OS is automatically detected before downloading from the Java Website. Casual internet surfers should use the JRE. The install package should automatically detect your operating system and architecture. This is where the divine apocalypse is set upon the world.
Operating system detection isn't a bad thing except for anyone using 64-bit architectures on Windows (which is increasing). Of the four people that had issues with downloading Java packages, they all had 64-bit architectures on Windows Vista/Windows 7 and they were downloading x86 version of JRE for development. The operating system detection failed and the users failed to download the proper package: this is all wrong.
If you too follow the footsteps of these harbingers of the Last Judgement, download the JDK instead and explicitly select the 64-bit version for your operating system.
JDK: Who needs it?. Software developers who write applets and applications using Java technology
The JDK is a little trickier to find because it was acquired by Oracle; thus, its binaries are found on Oracle's Website. JDK downloads are much more flexible because they allow you to select between x86 and x64 architectures for Windows before you download (instead of operating system detection).
I haven't tested it yet because I don't have a 64-bit Windows Vista/Windows 7 but it seems like operating system detection for JRE downloads is faulty. If you're having trouble with downloading JREs, just download JDK.