Hello!
Yes, it is possible to install Windows 7 build 7100 on your MacBook using an external HDD instead of CDs. You can create a bootable Windows installation on an external HDD and boot your MacBook from it to install Windows.
Here's a general outline of the steps you would need to follow:
1. Prepare the External HDD:
- Format the external HDD to be compatible with both macOS and Windows.
- Create a bootable Windows 7 installation on the external HDD.
2. Boot from the External HDD:
- Connect the external HDD to your MacBook.
- Restart your MacBook and hold down the Option key during startup to access the boot menu.
- Select the external HDD as the boot drive.
3. Install Windows 7:
- Follow the on-screen instructions to install Windows 7 on your MacBook.
Please note that this process may vary depending on the specific MacBook model and the tools you use to create the bootable Windows installation. Make sure to back up your important data before proceeding with the installation. Let me know if you need more detailed instructions on any of the steps!