Microsoft Mathematics 4.0 
Always wanted this program but even at $14.95 it was too expensive but with the 4.0 version it became free. It works great but it is limited take the simple heart function for graphs. When it is Valentine's Day and you want to quickly draw a heart virtually any graphing program would do. Except for this one.
I used this simple formula.
The results in any other graphing calculator is a pretty 
heart. I did confirm this in Maple, MATLAB, and GraphCalc. 
The results in Microsoft Math 4.0 is absolutely nothing.
I figure you have to transform the equation first but that defeats the purpose. When graphing it is good to know how to manipulate an equation but efficiency is also important.
Here's why this is a 70% program...
Pros
- Step by step equation solver 
 
- Nice interface
 
 Cons
- Does not graph well
 
- Difficult to change equations once written
 
Rating: 7 out of 10 (70%)
Got it at: 
Microsoft Download Center