I have lots of experience with this stuff, but why are you using a PIX and a SonicWall on the same network.

Also, I am assuming you bought 2 PIX fw's since you bought the FO license right.

Let me know specifically what you need, and I will help, but I do not know what your design included.

If you have multiple internet connections, (which is why I am assuming you have to firewalls) you will need to use BGP to take full advantage of routing capabilities, which also means you need to register an AS and you better have some hefty routers.

Is the VPN concentrator going to be inside or outside your FW?

But anyway, I have no idea what exactly you are trying to do, so let me know