I advise that you try MicroCUP v7 simulator for this purpose.
The program has a build-in analog filter design tool which is very friendly & easy to use. There are also some sample circuits.
**broken link removed** is a free LC filter design program.
You will need to know beforehand what frequency range you want to pass, what range to attenuate and by what amount, the load impedance and the soruce impedance.