The current MSVC builds of ReactOS (6561572) have an issue with booting (on real hardware, at least).
Installing ReactOS works fine; however, if the bootloader is installed to the MBR, the computer will not boot on the next restart (blinking cursor).
Attempting to boot via GRUB2 results in the following error: "error: no multiboot header found."
Installations from GCC builds boot fine from the GRUB2, however.
UPDATE: The MSVC LiveCDs also boot.