The short answer to that questions is no, a Will does not need to be notarized to be valid. Having said that, it is certainly the better practice to have your will notarized. The reason for this is that the signature of the testator (the person making the Will) should be witnessed by two additional people. The notary is certifying that he or she saw the witnesses sign the Will as well as the testator. If the Will is not notarized, then at the time of probate (the filing of the Will after death), your potential executor/trix will have to locate and bring the witnesses to the Register of Wills’ office. This can sometimes prove difficult if not impossible because witnesses may have moved or their whereabouts unknown. This will require the filing of additional paperwork at the time of probate.
A notarized Will is probatable without the need to bring any other parties other then the Executor/trix together with their counsel.
It is always the best practice to have your Will notarized and not merely witnessed.