IF Function - Too Many Arguments

Hi,
This is my first time to post a question, so please be patient.

I am using excel 2007.

I am trying to create a worksheet that will allow sales people to use a drop down menu in a cell to choose a text (species of wood) and by doing so it will assign a corresponding weight per board foot (a number) to the cell that contains the formula. I am trying to accomplish this by using an IF function and nesting all 11 of the species we produce in the formula but I keep getting errors.

Here's the formula:

=IF(I8="Ash",3.75,IF(I8="Basswood",2.03),IF(I8="Birch",3.6),IF(I8="Cedar",2.619),IF(I8="Hard&Maple",3.57),IF(I8="Hickory",4.2),IF(I8="Poplar",2.9),IF(I8="Red"&"Oak",3.7),IF(I8="Soft"&"Maple",3.03),(I8="Walnut",3.2),IF(I8="White"&"Oak",4.2))

When I enter the above formula I get the following error: "You have entered too many arguments for this function"

Help!!!
Thanks!