well, most will say 'memory cards are cheap'!
reason i suspect u are shooting in jpg is becos WB (IMO) is impt for people who shoot in jpgs. for those who shoot in RAW (is NEF), we can change the WB in either Nikon Capture 4 or PS CS2 (or other 3rd party software, as long as they can read the NEF file). thus, we will shoot in AWB mode and change the WB later to our liking. this option is not available if u shoot in jpg.
(dat said, the more pro shooters will say do everything rite in camera, including WB settings. and this will save u a lot of work later.)
there are a lot of advantages in shooting NEF, and lack of storage space is the least of ur reason not to do so. i will leave the advantages of shooting NEF to others to explain. u can also do a search on this matter. btw, computer illiteracy is also the least of ur reason. shooting digital will, inevitably, need some post-processing in the computer (yes, dat goes for all the fuji DSLR users too...). it will do u well to learn some basics of post-processing, whether on PS or NC4. dun use computer illiteracy as an excuse, and thus preventing u from getting the best out of the pics.
for 'correct' white balancing, as mentioned, there is no 'correct' WB. all depends on wat u want to achieve on ur shot. more imptly is to understand how ur camera 'sees' the whole. read
here for some basics. u can google more online.
if u really want to know more abt how to maximise the use of ur camera (btw, d70 is one heck of a camera. so, dun 'under-use' it), do sign up for the free nikon classes or join PSS' D70 introductory course, after u read ur manual and know how to operate ur camera.