You know, you can do it, but it isn't always easy. Use the procedure like SickMacdoc said. The few times I did it there was always something in one of the partitions I didn't or couldn't repartition without deleting and I ended up having to completely move stuff over from at least one of the partitions to an external and then deleting it. Oh, you know what the latest was now that I think about it; I had three partitions on an external: leopard clone, tiger clone, and backup and I decided I no longer needed the tiger clone. In order to get to just two partitions all correctly sized I ended up having to completely move the stuff I wanted off and then coping/cloning back over. That was a headache.