Let me add a little to the discussion.
MAKE SURE that when you get
any flea product for cats that it states right on the packaging that it is safe for cats.
There are many flea products on the market, but products which are safe for dogs are NOT always safe for cats. In fact, some of the most commonly used flea products (even ones which are only applied topically) are
outright toxic to cats and applying one to your kitty (even when following the directions exactly!) will almost always result in a seriously ill if not outright dead cat (not to mention a lot of guilt). This is unfortunately a pretty common mistake* due to inexperience on the part of the owner, the high turnover in today's pet supermarket stores, etc. Kati lost one of her cats to this after treating her brother/sister pair. One died, one recovered but suffered some liver damage (and managed to live to about 16yrs, though the last one was borrowed)
A quick Google search brought me
this page, which goes into some detail.
--Patrick
*relatively speaking. Don't give your cat Tylenol or Aspirin, either. Bad idea.