Hi, I had the same problem couple weeks ago, so let my explain you some of the things I've done.
SOLUTION #1: Using Windows
Would be great if you have another computer with any version of Windows because you could plug the HD to that machine as a slave disk and then use PartitionMagic 8.0 to see all the partitions of that "slave" disk. It's a program easy to use and will let you format the disk and change it back to NTFS system. That program it's not free but you could download a FREE-DEMO or Trial... It would be work I'm sure it will
SOLUTION #2: Using Linux
Another solution it's to get a Linux Installation disk, it would recognize your new HD and it could change it to NTFS system through the first step of the installation (you would not install Linux, just use it's installation disk to format the HD). Then you cancel the installation, reset the machine with your Windows XP disk and it's all done.
Let my tell you that these aren't professional solutions but they would be work on your computer. Post a Reply for any doubt.