From someone who's been scanning slides and negatives for years now (in fact, my second scanner is just about to break down mechanically from overuse)...
- save all originals (not just processed files, processing looses data).
- make regular backups to CD/DVD/tape. Harddisk crashes are becoming more common as harddisks get larger and more complex.
- make an easy system for finding your files again on the multitude of CDs/DVDs you'll end up with.
I made the mistake in the beginning of not saving an index file with the images, disaster if you need to browse through 30 20MB TIFF files each on 50 CDs to find the file you want.
You can either put an index on each CD or make separate index CDs (or do both of course).
At 20MB per scan (TIFF+thumbnail JPEG) you're looking at maybe 1 roll of film scanned onto a single CD-ROM...
- use a consistent file naming convention.
For the last several years I've used a simple convention, effectively naming each file with just a timestamp and serial number.
- title the CDs/DVDs in a meaningful manner. Date+location+(if applicable) topic are a good minimum.
- store the CDs/DVDs in the best possible archival system. Not just easy to find again but also correct climate.
- keep the slides or negatives. In 20-30 years noone may be able to read your CD/DVD either because it has degraded too far or because no software exists to read the file format you used, but a slide can always be read by simply shining light through it. If properly stored slides can last 75 years easily without loosing too much.
That's probably longer than you should vbe worried about them (unless you're the next Ansel Adams in which case you have no business shooting colour film anyway :)).