32 & 64-bit Java

Hello, I manage six 64-bit Windows 7 computers in our office. All are the same model purchased on the same date, and set up by me, two years ago. Today I was checking to see that our Java was all up-to-date, and discovered that two of us seem to be running 64-bit Java, while the other four of us have 32-bit Java (the Control Panel applets are ID'd differently, and they have different menu...