Well, I deleted my Leopard partition using Disk Utility, but now my SL partition did not take up the space left by the Leopard partition. How do I make it take up the whole HDD?
Can you drag the SL partition into the unpartitioned space above?
Then re-size the partition to fill the empty space below (use the dragger highlighted below):
Good idea, but it won't let me drag it to the above empty partition. But I might try doing the same while booting from my OS X SL dvd, maybe that would work.
Try to make another partition in the above empty partition. Then use the slider between the two partitions to increase the size of your SL partition.