Go to the library and get the book or DVD "The Happiest Toddler on the Block". This book has seriously changed the way I interact with my 2 1/2 yr old, I started reading it two weeks ago and no tantrums since I started the techniques.
They are REAL easy and really work-FAST! My son has not had a whining fit or tantrum (screaming, kicking, etc) that has lasted longer than 60 seconds. It works! Amazing.
Let me know how it works for you, I know how CRAZY those fits can make US.