How to boot from an existing Windows 7 partition under Ubuntu

This configuration could damage your Windows 7 installation, Backup you data.

Disk structure
Device Boot Start End Blocks Id System
Windows 7 /dev/sda1 * 1 46 364544 7 HPFS/NTFS
Windows 7 /dev/sda2 46 8515 68029440 7 HPFS/NTFS

# sudo apt-get install mbr
# sudo -i 
# cd .Virtualbox


Create mbr 
# install-mbr --force myBootRecord.mbr

Create your sda1 pointer
# VBoxManage internalcommands createrawvmdk -filename ./Win71.vmdk -rawdisk /dev/sda -partitions 1 -mbr ./myBootRecord.mbr -relative -register

Create sda2 pointer 
# VBoxManage internalcommands createrawvmdk -filename ./Win72.vmdk -rawdisk /dev/sda -partitions 2 -relative -register

Now you can create your machine and add Win71.vmdk and Win72.vmdk disks.