Random access memory, or RAM, is important if you are going to have a lot of different computer programs running at the same time. Also, some programs require more RAM than others, so depending on what you will use your computer for, you might need more RAM. DDR2 RAM is only compatible with motherboards that are equipped to handle DDR2 RAM. Before adding any DDR2 RAM to your computer, make sure that your motherboard will work with it. Some computer motherboards are compatible with only DDR or DDR3 RAM, which would make your DDR2 RAM worthless and possibly damaging.