I am a special needs teacher and my dyslexic and dyspraxic students use Dragon Dictate. You can navigate the web with it, use it to operate almost all the toolbar and it's recognition accuracy is about 98% once trained.
Naturally Speaking preferred version 7 is £130 at the moment and is what I use at home.
There is the standard version which is about £45/50 and it works fine.
There is and expensive professional version costing around £400.
All versions can have a number of different users so it can be used by the whole family.
I prefer it to Via Voice and Kurzweil.
It is from Scansoft and available through computer shops like PC World. Buy it from the web and look for the best deal you'll save lots.
Hope this helps, PM me if you want more details.
Good luck
Mary