There isn't a standard answer to your query, as your position will be dictated by your own specific circumstances. First of all, while the government has revealed that it will introduce a flat rate state pension of £144, this won't come into effect until 2017 so anyone retiring before then will still have to adhere to the current system.
In the first instance, you should get in contact with HM Revenue & Customs (HMRC) or the Citizens Advice Bureau (CAB). Until 1977, married women and widows could choose to pay a reduced rate of Class 1 NI contributions if employed, and not to pay Class 2 contributions if self-employed.
Paying reduced NI means that your contributions don't count toward some benefits, such as the basic state pension and bereavement benefits. However, you may still be able to get some help based on your husband's (or late husband's) contributions.
This means that you may be able to get an improved state pension based on your husband's NI record rather than your own. HMRC or CAB should be able to explain what options may be open to you.