Who Needs a Will?
Yes, you probably do need a will. Even so, not everyone really needs a will. If you're very young, very poor, and very childless with no special circumstances and nothing special you want to bequeath, there's really no need to make a will. For most people, the first stage of their life at which they really should make a will is when they have their first child. You must have a will in place if you want to decide who will care for your children if they are orphaned. If you don't have a will, and both parents die (think car wreck) a judge will decide who to place your children with, and their decision may or may not bear any resemblence to your wishes, expressed or written.
Components of a Will
Wills are surprisingly simple as far as legal documents go. To have a legally binding will, you need to name an executor. An executor is someone you trust who is not named as a beneficiary in the will to oversee the execution of your wishes. It's a big job and you need to make sure the person you name is aware and willing to do it. It's also not a bad idea to name a secondary executor in case the first is unwilling or unable to fill the role at the time of your death. You also need to have your signature on the will witnessed by at least two adults who are not named as beneficiaries in the will and who can testify that you are of sound mind and not being coerced. You can have the will notarized as well if you wish, but it is not a requirement. It's also a good idea to have a date on the will and include a phrase cancelling all previous wills and testaments. Some states will acknowledge handwritten wills, but it's a much better idea to type it up or use a form provided by your state.
Married Couples and Wills
Married couples are often tempted to make a joint will, like filing a joint tax return, in order to "hit two birds with one stone" so to speak. This is actually a very bad idea. Unless you've got a suicide pact or are otherwise certain that you'll die together, a joint will is a very messy business. When only one of the pair dies, the other is bound by the provisions of the will without being able to revise or change them as circumstances dictate. It's a much better idea to file seperate wills and make sure to put in identical information on the disposal of joint property as well as guardianship for any children in case your spouse is also deceased at the time of your death (or you do happen to die at the same time).