Microsoft will end official free support for Windows XP Home Edition and Microsoft Office 2003 on April 14th. That doesn't mean the help center on your computer will stop working, but you won't be able to get free answers to your questions from Microsoft anymore. You will be able to pay for extended support for both products through 2014.
Microsoft will also continue providing free security-related hotfixes to non-subscribing customers. So unless you frequently make calls to Microsoft support, the April 14th deadline might not really affect you.