He-he, once linux was installed that's all - your system is a part of a community, so don't even think you will ever boot into windows
The real answer is in question form, you stated you "toyed around" and boot into windows afterwards to do the damage, how did you boot there? To boot again do the same I guess. What are the choices in grub menu?
will erase grub boot loader from Master Boot Record so in the future you won't get grub prompt.
But still remember there are these words that had been permanently printed on your hardware: "
was here. And