Updates, the bane of any computer owner's experience.
You should always make sure your Operating System, be it Windows, OS X, or Linux is up to date with the latest updates. Why, you ask? Well, as a general rule those updates either resolve bugs in the OS, patch security holes in the OS, or add new functionality to the OS. That being said, you don't need to check daily for updates or anything like that. Once or twice a month is more than sufficient, and if there any critical updates that are released theres a good chance they they were widely publicized such as a flaw in Adobe Flash Player or Java.
Which brings us to software/drivers. Most computer manufacturers and component manufacturers release updates to their drivers (the software that makes a physical component function) and most software developers release updates for their programs. This can all be somewhat overwhelming. When it comes to software/drivers I feel the safest approach is "if it isn't broke you don't fix it" so if its working as intended no need to go hunt down those. Some manufacturers such as Dell and HP install software on the computer at the factory that makes checking for this a 1 or 2 click process, so you may want to do that about once a month.
Some helpful information on checking for updates:
On Windows XP-Windows 7 you can easily check for OS updates by clicking Start-All Programs-Windows Update
On Windows 8 I suggest you upgrade to Windows 8.1, you can do this via the App Store on the Start Screen.
On Windows 8.1 you Right Click the Start button->Select Control Panel->System and Security->Windows Update
On OS X you click the Apple icon in the top left corner and select updates.
On Linux it varies based on the build and version of Linux you are using, then again if you are using Linux, you most likely do not need my help :D.
Other useful information that may come in handy:
For laptops, always use the manufacturer's website for driver updates if you are experiencing issues, since a lot of laptops have customized drivers.
For desktops, use the component manufacturer's website. Such as Nvidia.com for an Nvidia video card or AMD.com for an AMD video card.
Microsoft releases updates for supported Windows Operating Systems on the second Tuesday of every month, commonly referred to as Patch Tuesday and more recently as Update Tuesday.
If you have any questions feel free to e-mail or call. If you aren't sure of how to check or if you need updates, the Tune-Up option under services covers checking for the latest updates on your system.