Fdisk...is a Win 9x tool, it's not needed for XP. The XP CD serves that function.
If you want to create/format a partition on a second drive...you have options.
You can use the XP install CD, where I suggest you delete all partitions on the drive as a preliminary step before creating the XP partition.
You can boot into your current XP install...and then use the Disk Management tool to delete existing structures, then format the partition. Since I have no idea what is your method of installing XP, I will assume that you have a valid XP install CD.
Another option, which you haven't mentioned...is simply to clone your current install to your second hard drive. This will give you an exact copy which can easily replace your current drive, should any drive/partition/file system problems develop which prevent you from booting or using that current system partition.
The key, of course, to successful cloning is to ensure that the drive is free of any malware or other problems...before making the cloned partition/drive. And updating the cloned drive (creating a new clone) as your system changes contents, programs installed, etc.
One such utility for cloning, EASEUS Partition Master is a magic partition manager software for Windows 2000-XP-Vista-2003- - http://www.partition-tool.com/
The free, home version.