|What you are looking for is called a "Nested IF".|
The arguments for an IF statement include a value_if_true and a value_if_false.
Instead of a "value" you can use another IF statement as those arguments. In your case, you would use an IF as the value_if_false arguments for the preceding logical_test.
Keep in mind that Excel 2003 is limited to 7 Nested IF's, so if you have more conditions than that, this solution won't work.
A Google search on "Nested If limitation" will return lots of hits with workarounds.
=IF(C3<801, 397, IF(C3<1601,545, IF(C3<3501,742, "C3 is Greater Than Or Equal to 3501")))