Well, I guess you wait until your new computer arrives, then you can install Windows on it.
One more question. Is the drive you are trying to format the one that is currently in you computer (the one you installed windows on your current pc with)? If it is, then you cannot format until your new computer arrives.
If that is the case, then to format outside Windows XP:
0. Boot up your pc.
1. Put WIndows XP into the CD Drive.
2. Wait for it to load up on the screen.
3. Select the choice to install windows.
4. You will appear at a prompt to format your hard drive.
5. Assuming you have your hard drive installed on your new pc, delete the partition on it (it will give you the choice at the disk partition screen.).
6. Now, in the free space on the hard drive, create a new partition on the hard drive (It will give this selection in the menu as well).
7. Select the new partition and select whatever looks like "Install windows on this partition".