NeoGRUB is an implementation of GRUB4DOS provided by the EasyBCD bootloader-configurator for Windows. When installed to the Windows bootloader (via Add New Entry - NeoGrub ) from EasyBCD, it embeds an implementation of GRUB Legacy inside the Windows Bootloader. This implementation can boot Arch Linux and other Linuxes directly, without chainloading a Linux bootloader installed on the linux's /boot.
This can be helpful if you find that updates to Arch are breaking your Arch's GRUB or Syslinux.
One caveat: NeoGRUB is only known to support the following filesystems: FAT16, FAT32, MINIX fs, ext2, ReiserFS, JFS, XFS that means that your /boot partition must be one of these filesystems if you use NeoGRUB. your / and other partitions can be whatever.
When you install NeoGRUB to the windows bootloader, click Configure. A configuration file window pops up, prompting you for GRUB configuration syntax for the NeoGrub. Here's an example to boot Arch Linux:
title Arch find --set-root /boot/vmlinuz-linux kernel /boot/vmlinuz-linux ro root=/dev/sda3 initrd /boot/initramfs-linux.img
adjust the /dev/sda3 line accordingly to point to your Linux / partition. Also, if you use a kernel other than default (such as linux-lts or the -ck kernel) adjust the initramfs and vmlinuz files accordingly.
More information of the nature and workings of EasyBCD and NeoGRUB is at the developer's site:
note that that last link has an example to boot Ubuntu. Ubuntu adds version numbers to its vmlinuz and initrd files, which would require that you update the NeoGRUB every kernel update. Arch does not have this problem. Also note that Arch uses initramfs, not initrd, but you still use the syntax in the code box above.