imho the norton security pack is a bunch of crap loaded on your pc that you don't need. last time i used it, it was very resource hoggy.
go to the admin panel of your linksys router
http://192.168.1.1
username : blank
password: admin (change that)
Setup WPA or WEP
Don't broadcast your SSID
there are initial firewall settings on the router to block ICMP ect ect.
there's lots of stuff you can do (for free) to keep the bad people at bay. but these are the basics.... and smart internet browsing is a big plus too.
hope that helps..
look in the linksys help files and faq to get the wep or wpa right.
if buying the norton av gives you a better feeling of security thats fine too. alot of people go that route and it works just fine.
just giving you a free alternative that i've used with success
good luck
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