Re: Is 30Gb the largest option during dual-boot install?
If you're going to dual-boot, then you need to do the following: Confirm that you don't already have the 4 Primary partition limit. To do this, open the Vista Disk Management utility and count the number of "drives" (that's what Windows calls partitions). If you already have 4, then you're going to be faced with a LOT of work because you will have to remove one before you can create another for Ubuntu.
Also, check the "drive" types and confirm they are NOT Dynamic Disks. Ubuntu can't be installed when Dynamic Disks are being used.
Use only the Vista Disk Management utility to shrink your Win7 OS partition to make room for Ubuntu. Do NOT use the Ubuntu installer to do this. If you already have 4 partitions in Vista, do NOT allow the partitioner to create another partition. This will convert your partitions into Dynamic Disks -- effectively preventing the installation of Ubuntu and causing you further problems.
Once you have Vista shrunk, when you then boot back into the Ubuntu installer, use "something else" to do the partitioning.
Ubuntu 16.10 Mate, Mint 18 Mate; MS Win 8.1, MS Win10 Pro.
Will not respond to PM requests for support -- use the forums.