Yesterday saw a bumper crop of security patches from Microsoft, Adobe, and Oracle (Java). Since of most of all y'all use these, you'll want to top up your security. Remember, it's like changing the oil in your car - you can put it off, but if you put it off too long then bad things happen to you.
Windows is easiest. Take Internet Explorer (you need it for this but shouldn't use it for anything else) to http:windowsupdate.microsoft.com. Simples. It's a once a month security oil change.
Adobe has important updates to Flash, which drives most video and a ton of ads. The biggest risk you'll face is malware coming via ads, so go get the update. Be careful with the update - Adobe packages a bunch of stuff with the patch (like McAfee's horrible Security Scan - not recommended), so pay attention and uncheck the bloatware options. You'll probably have to install twice - once for the OS and once for your browser.
Adobe also has an update for Reader (the thing you use to read PDF files) that you want to get. Malware has been embedded in PDFs for several years, so this is a credible threat vector. Unfortunately, there's no good way to hotlink directly to the update, so go here and search for Reader.
Java has been a sucking chest wound of security fail for a while, and this month is no exception - there are 36 security updates (!). If you haven't disabled Java in your browser (recommended) then you'll need the update because the Bad Guys are actively exploiting this. The easiest way to get the update is via the Java Console. - just remember that this will also automatically include crapware (the Ask Toolbar), so make sure you uncheck the crapware boxes.
I will leave for another day the rant about using critical security updates to fob off bloatware on an unsuspecting public ...