In future, it's probably easiest to simply uninstall any Sun java you already have, then install the new one. Too bad it doesn't work like some other well-behaved programs, checking for existing installations and offering to uninstall them before installing the new one and/or only adding update-patches.
Unfortunately each update/upgrade to the RTE is written so that it's handled as essentially a patch to earlier versions and added to them, even though it's a stand-alone. That's one of several things many of us wish Sun would clean up their act about (the other is that notorious "Check now for updates" which never works).
I'd recommend downloading (via the Manual Download link) what they call the offline version. That way it can just sit in your downloads folder while you do the rest of the cleanup.
(Afterthought) Incidentally, if you make use of the applet caching (very handy if you'e not critically tight on disk space), deleting the old version won't affect those and they'll still (usually) be recognized by the new installation. That probably means they're in Docs & Settings, rather than the program folder.