Compressed versus Uncompressed NEF
Nikon's D100 digital SLR supports shooting in both compressed and uncompressed Raw (what Nikon calls "NEF' for "Nikon Electronic Format") modes. When new D100 owners first venture beyond shooting JPEG's, they are sometimes mislead into believing that shooting NEF's takes too long to be of any use due to the time needed to write the results to the compact flash card.
The problem is, Nikon made compressed NEF the default, and it does take quite a while to compress NEF images. If you rotate the top left Mode dial to QUAL on a brand new D100 and select RAW by rotating the rear Command dial, you will be shooting compressed Raw (NEF). There is no good indication that this is the case, but it is.
To select uncompressed NEF, at some point you must do so via the SHOOTING menu on the back LCD. Navigate to "Image Quality" then to "NEF (Raw)" and finally to "NEF (Raw)" again instead of "Comp. NEF (Raw)." Once you have done this, not only will you have selected uncompressed NEF this time, but you also will have changed the default to be uncompressed so you can use the left Mode dial to get it again next time.
Nikon says that compressed NEF files are "virtually lossless" but they sure do take a long time to write to memory. Most users find that the extra space taken by uncompressed files is more than a fair tradeoff for the time saved by not compressing them. Try it both ways yourself and see. Just don't fall into the trap of thinking that shooting Raw is inherently slow. It isn't — only compressed NEF is.