I have shot almost 100% digital in the past 2 years, archiving is a lot easier for digital than it is for film. Imagine having to search through a basement of 100,000 shots to find the image you were looking for which might have been misplaced.

For speed, use a local 'network attached storage' device (NAS), you need a NAS with 'mirroring' with a technology called RAID.

You can back these up off site to a 3rd party. Amazon (yep the people that sell books) actually do a specialised backup service called Amazon S3. You can use software like JungleDisk to connect to this Amazon Service.

If you're worried about file formats then save (the untouched original) in uncompressed TIFF format, this will be totally future proof (as it's basicaly just RGB/CYMK values, no encoding whatsoever), some raw formats could become obsolete. Always make sure the bit depth is the same or higher than the orginal. Current PhaseOne and Leaf Backs both output 16bit files.

As for film, you can scan these in at a higher resolution (and 48bit) than the film grain itself eg 35mm=12-14megapixels (depending on ISO and stock). Then you can stick the film in a dry firesafe and hopefully never need it again!

For managing an archive I would highly recommend Adobe Lightroom, there are a number of utilities/add ons which make working with clients a whole lot easier.