No disrespect but the WindowsXP sp2 firewall displays as true stealth on the GRC test and passes everything… grc is nothing but hype to a certain extent, some of the claimed features such as nano probes is nothing but marketing hype as in this example they are nothing more than a standard syn packet
Read grcsucks.com and test the evidence for yourself, make up your own mind on what is true.
I always use sygate scan [url]http://scan.sygate.com/[/url]. GRC showed kerio and sygate as Stealth, when it wasn’t. Sygate scan showed many ports as closed - aswell as other scan sites. I had to uncheck all “act as servers” in sygate and kerio to be stealth by the sygate scan.
So GRC does not reflect a true Stealth status. Comodo passes with any scan site “out of the box” due to its block IP in rule. ;D
You’re right on the money. Gibbo’s site has got a lot of words in it, a few gems scattered amongst them and a pile of marketing and self-praise over the top of it all. By all means, read his stuff, but take a few grains of salt with it. 
Ewen 
(WCF3) (WCF3) (WCF3)