directly storage them in computer?
yes, the most recent images are always stored on one of my two internal disks.
would be too many DVDs And... CDs and DVDs can (and at some point will) fail, they are not 100% safe as they age!
backup them at your SD Card?
Using CF cards in the camera ... but if I wanted to archive on SD or CF I would run out of money very quickly
or backup them at removeable hard drive?
yes!
ok, here in detail:
1. I have two internal disks with together 400 GByte .. those are to store the current images I still work with
2. Then there is one (small regarding physical size) external firewire/USB disk used as an archive (700GByte)
3. And there are currently 3 further external disks giving together 900 GByte used to backup for my external and internal drives. Two of those drives are full now and stored at a place 150 miles away
So currently I have about 600 GByte of images, I would not want to burn those on DVD ... too mcuh work
Also I think harddrives are a rather safe option if you include a backup. If the backup disks have a different age and are from a different maker, the probability of your backup AND your primary storage failing at the same time is very very low. Of course you have to replace the harddrives before they come of age and become more prone to failure.
The good thing is, that what fits on 3 harddrives today will probably fit on one harddrive in 2 years time or so. I've been practicing this hard drive archival thing for many years now, starting with what I thought at that time a tremendous quantity of data and today the data from those early times is hidden in a tiny corner of my smallest harddrive. Never lost any data for 7 years now even though I started the additional backup thing just 3 months ago.
I know of at least one case where a photographer could not serve a client with a print of an old file since he could just not read the file from that old CD anymore. This fear of data loss , plus the fact I would need 1000 CDs or well over 100 DVDs for my just my current data keeps me from using CD/DVD for archival. my current archive including the backup fits into a medium sized shoebox (well, alltogether 6 harddrives).
