Increasing partition size?

Yes, at least if the drive is formatted as Mac OS Extended (Journaled) and you are running Leopard.

It will however require removing the partition immediately below it in the "Partition" section of Disk Utility though to free up space. First you need to select the partition that is directly below the one you wish to enlarge by clicking it once in the partition map. Then click the "-" at the bottom left which will remove the partition. That area will then become a grey block, indicating that it is now "free space" on the drive. Drag the lower right corner of the partition above the free space to the new size desired. If there is still free space available, you can click the "+" sign at the lower left and it will make a new partition out of the remaining space.

Click apply and a window will appear that will summarize what is going to happen (including what will and won't be erased). Click Apply if you agree with that and just wait a few seconds and you will be done.

 

iPartition can handle all kinds of scenarios.

 

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.