I duno what Windoctor does (what are you trying to cure?), but for defrag there are some better apps, one of them Diskeeper which I use sometimes as well.
One thing I know for sure that there is more slow downs from Norton stuff than speed ups, hear lots of questions about it. I use and recommend to stick with "light" stuff that does not hog the system.
..this is very useful and helpful place for information...