unless you are running a 64bit browser you have to get the file manually
here is the link to the 64bit offline installer.
Java 64Bit For Windows
If this still doesnt work download the linux version of the tekkit launcher
(its just a jar file it will work on windows)
right click on it and choose: "open with..."
click "browse"
navigate to "program files/java/javaw"
(NOT program files(x86)) x86 is your 32bit files.
this will tell it to always open your tekkit/technic launcher with 64bit java.
Happy Hunting.
Yankee~