No you don't. HDDs are though motherfuckers.
What has happened is that your computer isn't sure where to boot from. Most likely because your previous windows installation had a special hidden recovery drive and you installed a fresh one without recovery so now you have two bootable drives. This can be fixed (I've done it before) but it's a real pain in the ass. It's easier to just back up everything you have, format the entire HDD, and make a complete fresh install with new drives.