stupid Opera crashed on me after I'd finished typing my reply, only seconds b4 I hit post

I'm a newb too, I've got a simple network, no servers except samba server on my linux box. I have cable connection and realise that the cable 'modem' won't hide my computer so I bought a netgear router/firewall.
I was under the impression that the router was going to totally hide my network from 31337 kiddies I've set it to refuse all incoming requests, but allow all outgoing (software firewall should keep an eye on that)
I'm reading it's logs, and it has done well so far, dropping all incoming requests.. etc
Am I too complacent. I've checked my system with scans from GRC and broadband.com, etc and got total stealth reports. How good are these?
I've nmap-ed some of my freinds and family over the net and helped them to stealth their computers. If I did the same from another computer to my network is this enough?