Hi Christine
I have one of these:-
http://www.jean-patrique.co.uk/acatalog/Cookwa re_Store_ProCook__V__Professional_Knife_Sharpe ner_44.html
and it definitely works. Trouble is, it's not cheap (�40... but I waited until they had a sale and got mine at half that price).
If you are ok using a *steel* then one of them will sharpen knives properly, but do get a good quality one.
However, both of these items will only sharpen knives that still have a reasonably good edge... if yours are
totally blunt, they will need to be professionally reground or sharpened with a stone.