Help A Girl Out...

So I have this camera... a Nikon D50 to be exact. I love it. (Spent the majority of today in Central Park taking pictures. Snnnaaappppp).

However, I can NOT figure out one thing: how to transfer my new pictures.

Already, I've taken several pictures and loaded them onto my computer. Then the next time I go out and shoot, if I try to transfer the new photos onto my computer it only allows me to transfer EVERYTHING not just the new ones. In other words, I keep copying the same pictures over and over in addition to the new ones. So I guess my question is: A) Is there a setting I can put it on that will allow me to only tranfer the new pictures? B) Should I be clearing my memory stick after every download to avoid duplicating?

This is suddenly starting to sound like a Craigs List posting, a very G-Rated one. Haha...

I'm going to B&H tomorrow to get answers. But if you happen to know how to fix this, help a girl out and email me!!!! Tiffany.Simons@nbcuni.com