One of the benefits of having huge numbers of digitized document online is that digitized copies of the documents can be attached to individuals and families in our local genealogical database programs. But there may be a problem in thinking that just because a document is digitized, it is somehow preserved. A Blog appearing on the Library of Congress website, The Signal, Digital Preservation, has a recent post "Digitization is Different than Digital Preservation: Help Prevent Digital Orphans!" The author, Kistin Snawder, a Junior Fellow at the National Digital Information Infrastructure and Preservation Program (NDIIPP) at the Library of Congress, makes the point that "While scanning can be a prelude to digital preservation, the two are distinct."
I think the point is well taken, simply because you have a "digital" copy of a document does not mean that the document or the digital copy is somehow preserved. If you have custody of the original paper document, you still have the responsibility for the preservation of that document. Unless the documents were created in digital format, steps should be taken to preserve the original source as long as possible. Likewise, failing to take steps to preserve the integrity of the digital document obviates the effort made to digitize the original in the first place.
Preserving a digital file requires a number of steps, all of which are just as crucial as the physical care required for the preservation of the physical documents and artifacts. Both of these subjects are extensively covered online. I suggest starting with the Library of Congress' Preservation Directorate as a jumping off place for learning about both physical and digital preservation. For digital preservation, I suggest starting with the Northeast Document Conservation Center, "Digital Technology Made Simpler."