If you don't want to forget someone's birthday, you may consider using the reminder of your mobile phone to remind you when the birthday is near. It's not really hard to use. But if you want to use your computer for this task, you may download the reminder software to help you.http://www.celescom.com/downloads/alarm.exe
Try not to forget to give a present eventhough it's just a small one to let him/her know that you care for him/her.
