the shields up thing isnt really a security prog, more an advisor, it probes all your ports to see if they ping the server back or whatever, and highlights any weak spots

....a secure "stealthed" port wont even aknowledge its own presence by responding to any packets being sent to it, so to the potential hacker, they may be sending info to your system, and if they get some kind of reply they know they have found some hardware but "stealthed" ports appears to them that they are just sending data out into the either...


again im not vouching for how safe it is, but its a great concept.