I use cable and it's important for me to have a firewall
I use Look 'n' stop lite
fully customisable, light on resources, freeware, and very effective
I think you can get it here:
http://www.snapfiles.com/freeware/freeware.html
and I use Antivir Personal edition: also free, light on resources, also very fast, and I found it to detect more viruses than Norton
http://www.free-av.com