Effectiveness of Norton Without Updates

Okay I was just wondering how effective Norton Internet Security is without updates. I had NIS 2007 for about a month without updating it. I believe I was told that the firewall might be somewhat less effective, but is still good. What about the virus scanner and intrustion detection part? In case anyone mentions it, I already have the latest version of NIS, but I was just wondering how protected I was with outdated virus protection. Thanks.