Windows 7 Bootcamp refuses to format 20-gig partition to NTFS.

I just recently purchased a Macbook Pro 13-inch Retina at the close of 2012. Have wanted to install Bootcamp (5.1) on it, since I installed Bootcamp on my old Macbook Pro from 2007. Ran into a number of errors and roadblocks, but all were bypassed and there seems to be one final error that I cannot get around.

I am using an official copy, also recently purchased, of Windows 7 64-bit. It's installed as an .iso on a 16-gig flash drive. Upon starting the Windows installation on a 20-gig partition (created by the Bootcamp software), it asks me which partition I want to install Windows onto. I select Partition 4, which says BOOTCAMP, and then select "Advanced Options," where I attempt to have it format the partition from FAT to NTFS. I receive an error message stating that the "the recommended free space for installation is 24895 MB" and it refuses to format it.

There's no possible way that Windows 7 requires 25 GB of free space, I've done the research enough to know that. Why would it tell me that?? What is preventing me from using the install software to format the Bootcamp partition like everyone else seems to be able to do? Is there another issue that I'm missing?

P.S. Not sure if this is related, but there is an oddity in my hard drive's allocation of space: Disk Utility will only allow up to a 20 GB partition, and seems to think that the other 90 GB are necessary for my Mac's startup, even though I have approx 43 GB free, according to the information bar at the bottom of the Finder window.