Normally, the material presented to you in Software Update is tailored for your computer, and thus you do in fact need to install it. The only time I've seen it get confused is when (for example) someone USED to own an HP printer, but got a new one and never deleted the HP printer from the printer list. Under those circumstances, one would continue to receive HP printer updates (which do no harm whatsoever) even though they don't have an HP anymore.
In the case of the Digital RAW update, you're probably not taking photos in RAW format so technically you could skip that -- but it's supplying compatibility to iPhoto and Aperture in the event that you move to a more professional camera so that the support will already be there. Again there is no harm or significant space taken by installing it, and it keeps iPhoto/Aperture up to date, so long story short -- if Software Update says there are the updates you need, you should install them. You don't have to do it right that instant, but you should do them.