If not with dual boot, (using the Ubuntu Grub) I do not have another way to choose between Win 7 or Ubuntu when computer starts. But, basically my idea is to prepare when in 2020 Microsoft would not issue anymore security updates. By then, I would not use Win 7 to access the internet. The OS would be used to generate documents via Word etc. Ubuntu on the other hand would be my OS to search/access the Internet.
If you have any ideas on how to use Win 7 off-line on one hard drive and another OS (with security updates) on the other hard drive let me know. I like separate hard drives so the Win 7 would not be infected with viruses..etc
Thanks
Zavier