Blinking cursor on Bootcamp Windows 7

Hi everyone!

I gave my old MacPro 1,1 to my dad and used bootcamp to install Win7 on it.

As he's not familiar with OS X, I wanted the MacPro to always boot on Win7. But, when booting the MP the usual way, he always ends up with a blinking cursor and Win7 won't boot at all. I gave him the Alt key-press workaround, but it's not ideal.

I read that I had to boot on the Win7 DVD and fix the MBR. Thing is, the original DVD, when booting on it, gives me a "Select CD-ROM boot type" prompt, where the keyboard is not recognized and I'm not able to go further. So I burned a new one, and this time, even though I'm able to boot on it, when I want to repair the installation, I'm being told that the current DVD doesn't allow repairing on this type of installed Windows (I swear it's the exact same ISO that I've burned).

So, instead of burning a new DVD, I was looking into ways of fixing the MBR from OS X (the MP is running Yosemite). This time I read that I could boot on the Recovery HD partition to fix it. Somehow, and I don't know why, it won't boot on the recovery partition. It doesn't even show up in the disk utility.

Do you have any other way of fixing the MBR/Boot thing?

Thank you very much