Alright, let's see here.
Please keep in mind that doing this will result in all of your data being lost, so make sure you backup any info that is vital to you. Hook the HD up to your PC then follow these steps:
1) Go to start, and then right click on My Computer
2) In that menu you're going to want to click on manage (if you're using Vista you'll have to click continue)
3) In the root menus at the left, you want to click on Disk Management
4) Now if the hard drive is formatted for Mac, the disk management utility should see the hard drive space as "Unallocated" (which will show up as a black bar on one of the hard drives shown).
5) You'll want to right click the bar with the black bar on top and click on Create Partition
6) In the New Partition Wizard, you'll click Next and then Primary.
7) Decide how big you want the partition to be (typically the whole hard drive, but that's your choice)
8) At the next screen you assign a drive letter (your choice)
9) The next screen will give you a few options. The one you need to pay special attention to is to make sure that you've selected NTFS. No attention needs to be paid to the allocation size, and you can choose how to name the drive.
10) Click next, a screen will appear to validate everything you've done, and then click Finish.
After that it should go through the formatting process. Everything will be erased and it could take a while depending on the size of the drive. I believe there is an option to make it a quick format if you are impatient like me
