I woke up today with a clearer head than yesterday.
And realized with an MBR BIOS booting system, the BIOS sees each disk as a whole.
So, if I wanted to leave my Windows installation entirely intact (for safety, because the PC is used by other people), then I would need to have the GRUB bootloader on another disk.
But I want to use my SSD - which currently has a Windows Vista OS partition and an unused empty Windows partition (saved for a second OS) - for LL 3.0 .
Then the idea came to me - can I specify my other internal (slow) hard drive (used for data) as the location for the new GRUB boot loader in "Something Else" ?
Then I could use the unused SSD space for the actual LL 3.0 OS files (root).
After backing up my data from the Windows part of the SSD, I gave it a try and it worked fine.
I specified the slower hard drive "sdb" in the location for the boot loader, and then had Something Else format my empty additional D: partition for ext4 and mount "/" there and then I had it carve out 2gb for "/swap" as well and format that as well.
After the installation, when I rebooted, it went into Windows as normal - no problems.
Then in rebooting, I hit F12 and had it boot into the slower hard drive and then, sure enough, GRUB appeared and after the requisite 10 seconds, launched LL 3.0 .
So, not only is "Something Else" a great Miles Davis tune, it also will partition and format easily and simply, and will put GRUB bootloader whereever you want.