If you have Excel 2000 or newer, there are some very useful tools here http://www.pvconsultants.com/audio/frdgroup.htm

The crossover calculator is quite nice, but doesn't take VC offset into play. It should allow you to model the different hi and low pass filters with relative ease and has a Notch filter calculator and diagrams for everything.

"If you are flammable and have legs, you are never blocking a fire exit" -Mitch Hedberg