Restart the installation process and ensure all drivers are updated.
You can reinstall Windows 7 on a new drive if you have the original OEM disk. Just follow the installation steps using that disk.
You'll also require the code to enable it.
You need the activation key to proceed. Issues may arise if you attempt to modify the motherboard.
You have the activation sticker. Otherwise, I'm preparing a tutorial this weekend that covers obtaining your key from Windows. Keep an eye out!