how do I partition my hdd

I'm trying to partition my hard drive, so I go into disk utility, then into partition, and I can see my hard drive, and I can see the volume info and all that stuff, but I'm not able to partition it. the partition button is greyed out, and I don't know how to get it to work.
Can someone help?

You have to erase the whole drive to be able to partition it

so, I reformat, and when during a clean os x install, I'll be able to do it?

Start up your computer from a Mac OS X Install CD or an external hard disk with a System folder.
Open Disk Utility, located in Applications/Utilities. (If you start up from a Mac OS X Installer CD, choose Installer > Open Disk Utility.)
Select the disk that you want to partition in the left column .
Click Partition.
Choose the number of partitions from the Volume Scheme pop-up menu.
Click each partition and type a name for it, choose a format, and type a size (you can also drag the partitions to change the size).
Select the option to Install Mac OS 9 Drivers if you will use the partition as a Mac OS 9 startup disk. (You do not need Mac OS 9 drivers to use Classic.)

If you partition a removable hard disk, that disk is ejected when you eject any of its partitions.

thanks, trpnmonkey41, that worked like a charm.

Great thread.. I have to partition mine in the morning to install some yellow dog and keep osx.. I figured that was how you would go about doing it. How many partitions should I make? I've got a 80GB HD.. I was thinking going with 3-4..

You are not going to be able to "keep OS X". When you partition it erases the entire drive.

I understand that.. I will put it back on one of the partitions. And yellow dog on another. And keep maybe 1-2 more to store specific file types.

Actually there are tools that can repartition without erasing the current drive, but they cost $$$....

Yeah I know... I'm not going to spend the money... I won't mind doing a clean install..