I was wanting to download the JDK version 7 as I am using version 6 right now. However, when I was trying to download it from oracle.com, there were two versions for Windows available: x64 and x86. I'm a little confused about which one to download now. Hope that you'll be able to guide some way..I am using Windows XP Professional Service Pack 2.
First, are you sure you want the JDK, the JDK is for developers of java program, not users? For java that is designed for simply running Java programs goto http://java.com
and download. If you are a developer many IDEs include Java as part of their package (and I highly recommend getting an IDE if you plan to develop programs).
If you want to use Java with your web browser you should make sure that the architecture matches. If you want to determine the architecture of your OS you can (from http://au.answers.yahoo.com/question/index?qid=20080507041238AAkW95t
Go to Start Menu > Run. Type msinfo32 and click OK. A Window containing your System's information should appear. In that window look for 'System Summary' and look for 'System Type' in that. From that you'll know if it is x64 or x86.
x86 is the "safe" choice and should work on x64. If you choose the x86 version you will be limited to using no more than 4G of ram when running your program. Any program you make will still be runnable on x64 or x86 computers running Mac, Windows, or Linux (with the possible ram limitations).