At home I use only 64-bit versions of Windows 7. At school, my laptop remains the original 32-bit install. Despite that, I use the 32-bit version of Java at home (and everywhere else) because it is just so easy to get.
However, the 64-bit version does offer some enhancements. On every computer I compare with, the x64 Java is always 30% faster. I think everyone agrees that Java needs to be faster. Only the 64-bit version of Java will work with the incredible x64 Eclipse.
Java.com’s explanation of whether or not to download the x64 version is kind of silly as it focuses on if you use Internet Explorer.
If you’re looking for the 64-bit version of the JRE or the 64-bit version of the JDK, you can find those at the Java SE Download page.