I highly recommend everybody (especially those involved in security) subscribe to the Department of Homeland Security's US-CERT Cyber Security Bulletin Vulnerability Summaries
. Browse through the archives and note the reported vulnerabilities. You will be amazed (or I was anyway) at the vast number of newly reported vulnerabilities for Adobe products - almost weekly. Firefox is, by far, the leader in newly reported vulnerabilities, with Chrome not far behind and I use that often to quash unfounded MS and IE bashings as IE8/9 continues to prove it is the most secure browser - for nearly 3 years running.
Also worth noting newly reported vulnerabilities that keep showing up for Linux, and Mac products - good for pointing out to those user who insist their Linux or Mac systems are incapable of being compromised.
I am always leery of reports sponsored by specific product makers - especially those who compete with MS. However, as Corrine noted, no MS products made the list and I think that says a lot for MS, and for Kaspersky for pointing that out! I also like that they stated the reason, "This is because the automatic updates mechanism has now been well developed in recent versions of Windows OS."
That illustrates not only how important it is to keep our 3rd-party apps updated, but Windows/Microsoft products as well. And it illustrates how effective that is at keeping us safe.
I have not tried Sumatra PDA, but do use and recommend Foxit Reader
And for those who like NoScript but use IE, I highly recommend and use AdblockIE
(no space and not the same as, good as, nor to be confused with "Adblock IE" - with a space).