Norton Internet Security 2009 impressed us when it first appeared in September. It's the lightest Norton-branded product yet, and its resource demands look good next to the competition - though in this month's tests Eset and Kaspersky managed to slightly undercut its RAM requirements.

We were also impressed to see Norton achieve malware detection rates comparable to Kaspersky's, then our A List choice. That's still the case - with 86% in this month's test, Norton scored just 2% less than its rival. Sadly, in this company that falls short of the winners' podium.

When it came to web threats Norton dropped further behind the front-runners, flagging up only 34% of our malicious sites. Its defence against our network attacks wasn't the most convincing either: as with McAfee, it left three TCP ports open along with a few other high risk vulnerabilities.

It's a shame, because Norton Internet Security 2009 has obviously been designed with good intentions. Not only is it lightweight, it's also unobtrusive: warning you of malware detections with a small, self-closing pop-up in the corner of the screen. And it doesn't visibly modify your email client in any way, though it steps in when it finds infected mail.

Unfortunately, this well-meaning reticence is frustrating for technical users. Requesters can be vague about which virus was found or where, and the juicy details are buried behind an overcomplicated interface.

Despite those gripes, this edition of Norton Internet Security is light, credible and a very welcome advance over previous Norton products. Next to the likes of Avira and Bullguard, however, its test scores look disappointingly average.