umm, you are aware that "Stealth Mode" on most routers only disables ICMP replies? It's not a panacea.
Sorry, I should have said "stealth mode
NAT router" - it's the NAT that gives you most of the protection.
Yes I do know about ICMP, I mostly do comms software for a living. What the stealth mode might give you is that a port scanner might give up, due to lack of replies due to stealth mode, before it hits something it could use. Of course if you have no open ports through your NAT box there'll be nothing it could use anyway ...