Economics involving calculus

any software to recommend to plot a demand curve?
i need to deduce the equation of the curve given a data of points but i have no idea how to do it!!! please help!!!
the data is as follows:
Unit Price (P) in $ Quantity Demanded (Q) in units
0 500
5 450
8 372
10 300
12 212
15 50

Hey lilrainbowsky.

Do you have Microsoft Excel?

Yes yes!! I do have that! 2010 version. Do you have any idea how can I do it?
Thanks a lot!! :)

An example of linear fitting:

Data Fitting Using Excel.

An example of non-linear fitting:

Microsoft Excel: A Turorial