Can anyone tell me what the expected storage life is for electronic media such as tapes, CD’s, floppies, etc?
The three types of storage media you mention have different lifespans for different reasons and based on many different factors.
• Ordinary FeO[sup]2[/sup] magnetic tape holds data through the wonders of magnetic hysteresis, but the data can be affected by stray fields & will eventually lose its strength over time. Do you play back the tape much? Excessive replay will wear the FeO[sup]2[/sup] coating off (that’s part of the grime you clean off your tape heads).
• CDs are near perfect storage devices (the stone tablets of the 20th century) because the data is encoded in physical pits on the disc. These pits don’t wear our or get “weaker” over time and aren’t affected by stray magnetic fields. The only thing affecting CD lifespan is environmental erosion (being touched by human hands, left out in direct sunlight, etc.)
• Floppies are magnetic discs and are affected by stray magnetism just like FeO[sup]2[/sup] tape. What I don’t know here is whether or not the head comes into direct contact with the disc during read/write.
If you’re trying to make a digital data time capsule, CDs are your best bet. Locked up away from the environment, their data will still be there fresh as ever in a million years. Of course nobody wil have a clue what to do with it a million years from now. 
The BBC recognised the short life span of magnetic media and would not commit its sound archives to tape but preferred the good old fashioned vinyl disks.If they have changed this policy with the advent of CDs I do not know. Another disadvantage of magnetic media is that it can be effected by the magnetic radiation from nuclear explosions.
This link sets the life span of a CD, if properly cared for at ‘over 200 years’… not quite near-perfect by any means.
What can affect them? CD rot! Which is caused by oxidation of the aluminum through flaws in the plastic foil casing.
Furthermore, a not very large dose of microwave radiation can completely destroy a CD as aluminum turns fairly brittle when hit by it. If you want to see an example of this (and a cool light show) put a CD in the microwave for 3 seconds. Note: It will no longer be playable afterwards.
I put far more trust in the HD-Rosetta which etches nanometer-sized marks into a silicon disc with an ion beam for near-permanent storage.
Of course, the cost is prohibitively high.
Won’t it just catch on fire, like aluminum foil? Or are we treated to a laser light show before the flames? I’d prefer not to burn down my house in an experiment. 
I believe the quote for a CD’s life that I know of was more like thirty years.
I don’t think there is really any need nowadays for it to be any higher. By that time, CD’s will be defunct and some other form of media will be around.
Plus, why would the companies want to produce a form of media that lasted forever? Surely that is one of their reasons for making people up-grade.
The only way I can think of for storing information for ages, would be some kind of recording crystal or summat. Possibly not… it’s still a long way off, anyway!
It is more complicated than that for CDs.
There are at least two types of CDs. The prerecorded CDs and CDs you recored your self on your computer. They are different. The prerecorded CDs are what people have been talking about previously on this thread. CDRs have some kind of die which is changed with heat from the recording laser. I presume that the CDRs last a shorter amount of time but this is just based on the idea that they are easier to make not real data.
Your CD in the microwave gets a huge dose of microwave radiation to cuase it to burn up. It is just not as huge as is needed to cook dinner. sethdallob they are great fun in the microwave the only problem is that they smell bad. just stick them in for a few minutes.
CDs like most everything else last longer if stored in a cool, dry, dark place like the pots where the dead see scrolls were found.
You know, back in Sumeria, I’m sure some guy was saying, “I don’t see why we should preserve all these cuniform tablets. Who’s going to care about them in 1000 years?”
Fair Enough.
But back then, the people who were writing stuff down were not owned by huge, money-grabbing, multi- nationals.
If someone really wanted to preserve info, stone structures a la Stonehenge are probably the way to go… but then in 1000 years, a few new-age hippies would probably be dancing around a (stone) copy of a Britney Spears album or something!