I think that its probably either a bios update u need or...
You probably need SP2. There isn't really a tool for it, it just allows bigger hard drive addressing.
well you'd need to user partition magic to resize the partition to use the entire drive, OR, if it's not your system drive kill the main partition on it and assign it new, OR, goto disk management and format the rest of the drive as another parition and assign it it's own drive letter.