RE: Avast Internet Security vs Norton Internet Securtiy
As much as I like Avast [and I respect the company a lot for providing one of the most fully-featured free products], I'd have to pick Norton, although it's a close call.
Norton have come a long way in the last 2 years, and although the footprints are similar, Norton just feels lighter and more responsive. It's also really compatible and I haven't experienced any conflicts with other software. Haven't seen much of the silent firewall [it seems that the name is fitting]. Outright whole product dynamic tests do give Norton the advantage of better detection and it does it fairly quietly and unobtrusively. Update speed is second to none.
Avast is now a sleek and polished package which combines strength with enough visual flair. The guards are plentiful and although the options to customize their behavior are exhaustive, it feels like they have a way to go to still. Cannot comment on the firewall, because I switch it off for better compatibility with other Firewall/HIPS software. Love the idea of SafeZone [proprietary browser technology should increase protection] and Sandboxing [better usability than BufferZone in some aspects].