Who says 5.25" floppies are obsolete? Here's how to get them to hold up to 8.54 GB of data (kinda).

[edit] Steps

Get your disks and an X-Acto knife.
Insert the tip of the knife into the tiny hole in one of the top two corners of the disk.
Cut along the top edge of the disk, keeping the knife angled so that the blade is cutting up from underneath, rather than cutting down into the edge. Try to keep the knife closer to the front side of the disk.
Once you've cut all the way across the top, remove the magnetic disk (but not the pads inside the sleeve), then flip the disk onto its front and pull off the tab that is on the back along the top edge.
Label the outside of the disk, and insert the CD or DVD of your choice.

[edit] Tips

Try not to insert the knife too far into the disk as you're cutting. This will prevent the knife from tearing up the pads on the inside of the disk sleeve.
Keeping the knife at the proper angle will help you cut in a straight line and not accidentally cut into the sides of the disk.
Don't remove the pads inside of the sleeve. These will provide added protection for your CDs.
If you're concerned that your CD or DVD could get scratched through the oval shaped hole in the disk, store it in the paper sleeve it came with.
If you've got one of those old plastic disk storage boxes, this will add to the retro effect.