creating a new volume undestructively? (with Disk Utility)

Hello everyone,

I have an external 250 GB HDD which has a 120Gb Mac OS Extended Journaled partition, the rest being free space. I'd like to create a second volume out of the free space which exists, using the Disk Utility. What I'd like to know is whether this would erase the data I already have on the existing partition (the first volume) or will leave the existing partition unaffected?
I know in Windows this wouldn't affect the existing partition, but with Disk Utility I'm a little worried, as after I choose the partition type and name for the partition to be created and I click on the "Partition" button, a warning dialogue opens saying:

"Partitioning a disk will destroy all the information on volume of the disk

The disk has 1 volume
"Name_of_my_existing_volume"

Are you sure you wish to partition the disk?"

Thank you in advance,
Cheers,
Horea

As long as you ONLY create and format the partition that's shown as free space you are in no danger of overwriting your OS X partition. Disk Utility more or less does the same thing as the Disk Administrator does in Windows XP.

However, in order to stay one step ahead of Mr. Murphy, make a verified backup of your entire hard drive before proceeding.

Regards.