When you get a new computer usually there are a number of programs included that it asks you when you start it if you want to install. Many of these are trial programs you can use for a month or two.
The programs usually include an antivirus program, an office program and picture programs. I suggest installing the ones you will use or want to try but not others. If they ask to install a toolbar or search program I suggest normally saying no to the toolbar or search program.
Remember when you install the trial ones either you have to buy at end of trial or get another program if you want to use that type program. Some offer good prices to upgrade to full version online and some are high. Microsoft has had recently good deals on upgrade from trial.
Make sure you keep an antivirus program on your computer and keep it updated. For a free antivirus program I suggest AVG at avg.com Some ISPs let you use Norton or McAfee for free.