Welcome to the board. Most of those hairball remedy foods do not help completely, they don't have enough of whatever it is for hairballs in them to be "therapeutic." One thing I'm going to suggest and as silly as it sounds it really does help... have your cat shaved into a "lion cut" which means, everything goes except her head, neck, feet and bottom of the tail. She may look funny for a while but it really will cut down on hairballs. We do a lot of these now where I work (many groomers won't do them because some cats do require anesthesia to be shaved but most times we don't need to use anesthesia), even our hospital cat has the lion cut!
Good luck!
Cat =^..^=
Edited to add: do a google search for "lion cut for cats" and pictures will come up to show you what it looks like.
Edited 10/20/2009 7:27 am ET by cl-catwoman_ri