Clean install - Incorrect platform (AMD or i386)

Hello everyone!

This is my first post & I used FreeBSD a few years ago, starting with 3 & going up to 5 Stable. I used it as a gateway for my home network & as a firewall. Now, I want to play around with it again as a hobby in a dual-boot setup with Windows 7.

I much prefer installing FreeBSD 11.0 Stable or Release first on a clean install, and then installing Windows 7 after that. I recently tried this using the CD .iso of 11.0 Release. Using the guided installation, I tried to install it on my RAID-1, which I had just deleted & reconfigured in my BIOS. It gave me an error that I cannot quite recall; If I remember correctly it was "Incorrect platform" or maybe "architecture for this setup". I was not ready to try using the manual method, so I just ended up putting Windows 7 on alone.

I feel like I should be able to do this, and I hope someone could point me in the right direction.
Here is my hardware setup, and I will be starting with a freshly-wiped out RAID-1 -- Deleting both volumes in the BOIS & setting them up as a single disk.

Intel Core i7 X64 processor
Intel X58 ICH10R
AMI Bios
Marvell 88SE9128 Controller PCI E RAID-1 (SATA-as-IDE)
(2) 1 TB hard drives (set as 1 hd RAID-1 with 1 TB capacity)
12 GB DDr3 RAM

For the installer image, should I grab the AMD64 image or the i386 image? I am
thinking that i need to get the amd64 image, but I am unsure what caused my
previous installation image..... I could solve that by getting both images, but I also
wonder if I encountered some problem because I was trying to install it to a freshly-erased
large RAID-1 disk setup... I am open to using GPT or MBR - I don't have any preferences
as to which. I am also open to booting into Live-CD & just creating slices for FreeBSD & committing the changes, and then installing Windows 7 & setting it up & coming back to play
with the FreeBSD installation later. I will use the traditional /, swap, /var, and /usr for partitions
based on a 38 GB or larger portion of the hd.

Many thanks in advance, and I look forward to the challenge (and fun) of
using FreeBSD again !! :) ;)