I, too, have multiple entries for Java in Add/Remove programs.
There are several 5.0 updates plus 6 update 1, 2 and 3. Can I just uninstall everything except the 6 update 3 or should I uninstall them all and manually download and reinstall 6 update 3?

And which one should I download? They have two links on the download page. One file is 7.1 MB and the other is 13.92 MB. Both are labeled the same, but link to different files.