Regarding the Use of Digital Data in Court?

iChuckles asks: "Is there a way to make electronic data admissible in court? Can electronic data be used as an alibi? I want to keep an electronic journal, on my work, that is date and time stamped. This journal could be used to prove I came up with an idea on a certain date based upon an entry. Is there a database, or method of recording this data, in electronic form, that will stand up in court? Is there a database that once a record is entered with an accompanying time and date stamp, cannot be altered?"