what do i need to format part of a working harddrive

when i was installing xp pro it asked where i wanted to install the os and how much room i wanted alotted for it.i wanted to have 2 partitions or more so i just chose 10gb and its a 30 gb harddive,so i cant use the other 20 so how can i format the rest of the harddrive without formatting the entire harddrive.the harddrive and whole computer are new so the rest of the harddrive is raw,is there a program i can use to get this harddrive fixed.thanx

open the control panel, and go to administative tools (under performance and maintance if yuo're in category view). then open computer management and click disk management under storage. this will let you create/format/delete partitions. you can also use something like partition magic (lets you resize partition without destroying data).

thanx man that worked