I wouldn't recommend using two firewalls. Just get a really good one and stick with it, it should work fine. I use Sygate and I'm happy with it.

You sound like your serious about securing your system. Just make sure you got Virus Scanner (I recommend PC-Cillin) and a good firewall (like Sygate). But, don't think you are invincible then - you still gotta be active and make sure to not open any suspicious emails, etc. But, it should be suffice for a home system.

Greg