That is the key - how valuable is your data? Many times I have burned 2 CDs - 'Just in case...' I have data files and even copies of programs that go back to 1985 - 86. Important floppies I transferred to CD when I got my first CD writer. Before that I wrote them to Iomega bernoulli disks (starting with the 8" 5 megabyte magnetic 'floppies' for any of you who remember them and then to the 20 megabyte 5" disks - both of which internally were flexible disks). If I get nostalgic at some time I'll bore you by recounting my experience with Iomega, Jerome Johnson and the old SF Home Brew club that he came from (the same one Woz, the original Apple hardware designer, was in). I worked as a consultant to Iomega with Jerry Schlagheck when Iomega made their first storage box with SMT (surface mount technology) devices (which is also how I got my early experiences with Ford - and thus 'automotive' {with Ford it was their engine computer}). My life back then was troubleshooting electronics from manufacturing processes to board design and layout to finite analysis of assemblies (another project I was involved in was the Bradley Fighting Vehicle main computer reliability). I still have those and the old Bernoulli box and a computer with the software and scsi interface to run the box - but I did transfer everything off the Bernoulli disks when I got a CD burner so it's toast other than as memories of 300 and 1200 baud days with the exception of hardware and software issues.
I'm telling you this little story because it goes beyond the media to the application and hardware levels. You have to ensure that in 10 years you still have both the software and the hardware to read the archived data. Sometimes it won't matter. E.g.: ACSII (plain text) files from years ago are still readable by many, many applications. But - as an example - I had a version of FrameMaker for Mac from back in 1988 that I wrote my first 'book' in. Today I would be hard pressed to open that file. I'd have to pull my OLD Mac Si out of the closet, set it up again, use a 12" monitor I've saved for use on 'any old Mac' and - hope... I haven't looked at that file in years. Framemaker still makes a Mac version, but I'd bet the current version wouldn't open a file from 1988...
if your data is important to you and time is an issue, remember there is more to it than storage medium.
EDIT ADD: I saw the last post about being redundant. When that is an issue we're beyond archiving. If realtime is an issue you have to have a multiple location setup where a RAID or other mirroring technique is used with a central server so that any time a satellite location drops out a remaining location picks up and distributes the traffic. I am mostly familiar with this with respect to web sites. If my server fails, whether it's a local connectivity issue or a drive failure, how is the 'void' filled? In the case of this site, if a drive fails I do have a backup drive mirroring this one, but it does not 'take over' automatically. And if my connection fails, I have no redundancy. I could do it but the co$t is a bit much. I had an insurance company as a client once - They had a central server and they mirrored, in realtime, to 4 geographically diverse locations. They also had a failsafe for the main server going down including auto-magic domain IP forwarding so even a catestrophic failure at 2 or 3 locations would not seriously affect them.