What's the best software out there to LEARN math with for adults? I was in a car accident years ago and lost all but basic math skills (i.e. addition, subtraction, division and multiplication). I'd like to relearn algebra then continue on with geometry, calculus and trig.

A program that is easy to work with, has a high success rate and allows me to upgrade to the next level (without having to change software) would be ideal. Any suggestions?