It is futile to use those optical disc as a long term data storage solution. They might be great for holding large amount of data cheaply -- be it 700Mb for CD-R, 4+Gb for DVD-R or more when you add in acronyms like DL or HD. However, all of them stuff up over time. You either get bad scratches by over-using them, the dye might degrade over time because of weather or sunlight, or it might be digested by the evil fungus! So I ended up having quite a few CD's that are no longer readable, and subsequently added to my frisbee collection. Fortunately, nothing important has been lost, and I shall always remember to re-backup those CD's again in newer media every now and then.
Of course there is also another risk. Shining round-shaped plates can sometimes attract young children, who might attack your precious data by taking it out from the jewel case, scratching it, bitting it, and then smashing it against the floor. Demonstrated by our lovely Anna here. Boys and girls -- don't try it at home.