There are lots of articles regarding archiving, but this sums it up nicely: basically, if you want to keep images, do not just rely on CD..
http://web.ukonline.co.uk/suttonelms/articles9.html
Personally, my archiving is as follows:
C Drive - contains only images I am editing or using (copied)
D Drive - this is Backup '1' for all the images I keep - I use this drive to pull copies from.
External Drive: All original images are stored on the externall HDD.
I also use CD-R as a secondary backup.
I annualy replace the discs, and do straight copies.
I also *add* (on the basis that a HDD can fail at any time) a new external drive roughly every 18 months. I then move the original images to the new drive, and copy them back to the old external, which is then stored off-site.
I also have several Flash keys, which I intend to use instead of CDs from now on. (In fact, I have just placed an order with MX2 for another half-dozen 2 gig Kingstons).
A bit OTT for most, but I cherish my image collection, and, particularly now I am no longer archiving to CD, it is relatively cheap (at the rate I take images and replace external drives, about 35GBP per annum, plus maybe a tenner for the odd flash-drive. It's worth it for me anyway!
I may even stop using HDD storage altogther, as solid state is just getting ridiculously cheap these days - plus it saves space and wiring!!