Basically getdate() is not deterministic. It is possible to call getdate() from a function by tricking the server but this will cause the optimiser to give an incorret plan (it expects the function to be deterministic) and queries to give incorrect results.
As Merkin says you have to pass the value to the function.
========================================== Cursors are useful if you don't know sql. DTS can be used in a similar way. Beer is not cold and it isn't fizzy.