Keeping your software up to date is a great way to make sure things are running their fastest.
Developers are continually updating their software. They fix code errors and optimize the current code. This makes the software run faster, less likely to crash and so on.
Just make a point of setting your software to check for updates or do it yourself.
Some applications don't have anything that let's you check for updates though. In this case you can go to the site where you downloaded it and check that you have the newest version.
But let's face it. Do you really want to do this with ALL your applications? I don't think so.
Luckily I know a good solution.
Download the AppUpdate widget. It's a widget that checks that all your software is up to date. It makes all this much easier and quicker.
Read more about AppUpdate here.