This guide is adapted from http://reboot.pro/topic/14547-linux-load-your-root-partition-to-ram-and-boot-it/
What you need:
- lots of RAM
- Debian based distribution or any that supports booting from initramfs
- mkinitramfs or a tool to build a new initramfs
- some linux knowledge
- no need to create an image
- no need for Grub4Dos