Thank you for your reply. You're right (I was wrong) about /dev/sda4 and /dev/sda5.
Yes, I'm somewhat comfortable editing partitions. I say "somewhat" because I'm a bit apprehensive about making changes that carry much risk!
I plan on using Mint much more often than Ubuntu (for every one boot into Ubuntu, I plan 100 logins into Mint). So, yes, I think it would be good to not have a GRUB menu dependent on keeping the Ubuntu distro.
When I installed Mint 13 a few days ago, I installed MBR on /dev/sda/. I think "sda" without a number appended means "hard drive".
Vincent Vermeulen wrote: And if you don't want Ubuntu to hijack the MBR with its GRUB, tell it to install GRUB to Ubuntu's new root partition (/dev/sda7).
I understand the instruction, but I'd also like to understand:
Question 1: Why does installing GRUB to Ubuntu's new partition mean that Ubuntu won't hijack MBR?
Question 2: If I do go ahead and install GRUB on Ubuntu's new partition, won't that mean that if I remove the Ubuntu partition, I'm left with no GRUB?
Question 3: Or, to to ask a similar question: How can I update the boot-menu (GRUB) if I later decide to remove the Ubuntu partition?
Question 4: Is a partition of 4 GB spacious enough for Ubuntu? To know how much space a distro is most efficient with, do I simply just need to see how much space it takes on the hard drive and add a few MB of extra free space? The reason I'm asking about this is because I want most of my Linux space to go to Mint, and only the minimum (but not too small to create a slowdown) to Ubuntu.