You do not need to re-install Ubuntu to build the Ubuntu/Windows 8 preview guest system, and then restore the Ubuntu method.

You do not need to re-install Ubuntu to build the Ubuntu/Windows 8 preview guest system, and then restore the Ubuntu method.

1. Go to Windows and use the ultraiso tool to convert the ISO Security CDs into Windows USB Security labels.
Start ultraiso Software
Click "open" and select the Windows 8 Customer preview ISO image file you want to write to the USB flash drive.
After opening your image file, click "start" in the main menu and select "Write hard disk image"
After entering, you can select the USB flash drive you want to write to (if it is a Windows 7 system disk, it can be a USB flash drive larger than 4 GB; for the ISO of Windows 8 Customer preview, 4G or above U memory is also required)
For safety, to avoid making the U disk boot disk can not boot the computer, we choose "Write mode", choose "USB-HDD +"
After selecting the write mode, click "write" below. Wait until the entire write process is completed! (In fact, it is just copying the image file to the USB flash drive)

2. Installing Windows
When you are on the machine, select "U" to activate the drive. Normally, Windows 8 Customer preview is installed.

3. Restore ubuntu)

Start the computer with ubuntu10.04 and enter the livecd mode.
Sudo-I

Find the partition where your ubuntu10.04 is installed, and use:
Fdisk-l

Some of my outputs are as follows:
Disk/dev/SDA: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 Cylinders
Units = cylinders of 16065*512 = 8225280 bytes
Sector size (logical/physical): 512 bytes/512 bytes
I/O size (minimum/optimal): 512 bytes/512 bytes
Disk identifier: 0x35fa7d7b

Device boot start end blocks ID system
/Dev/sda1 1 10574 84935623 7 HPFs/NTFS
/Dev/sda2 10575 60802 403449850 + 5 extended
/Dev/sda5 21123 22119 7999488 82 Linux swap/Solaris
/Dev/sda6 22119 32078 79998976 83 Linux
/Dev/sda7 32078 60289 226601984 83 Linux
/Dev/sda8 60289 60802 4118528 82 Linux swap/Solaris
/Dev/sda9 10575 21122 84726747 83 Linux

Partition Table entries are not in disk order

My ubuntu10.04 root directory is located in/dev/sda7. If you are not sure, find the ID 83.

Mount the root directory of the original system as follows:
Mount/dev/sda7/mnt

Mount/dev/sda7 to/mnt. You can also choose another place. Note that if you have a separate/boot partition, You need to mount the/boot file once separately. For example, if your original/boot file is mounted to/dev/sda12, enter Mount/dev/sda12/mnt/boot. I didn't separate it here, so I don't need it anymore.

The following is the last step:
Grub-install -- root-directory =/mnt/dev/SDA (note: the Space key is behind/mnt)

If you see
Installation finished. No error reported.

It indicates that it is successful! Restart and check if the familiar GRUB boot screen is back again?

Restart your computer and you will be able to see the grub2 boot interface. However, it can only be used to guide Ubuntu 10.04, but Windows 7 cannot be guided for the moment. At this time, you can choose to enter Ubuntu 10.04, find and start the terminal, and enter the following command on the terminal:

Sudo update-grub2

Update grub2.
Follow the prompts to enter the password. If the password succeeds, the following similar statements will appear, indicating that the password is successful.
Generating grub. cfg...
Found Linux image:/boot/vmlinuz-2.6.38-13-generic-pae
Found initrd image:/boot/initrd. img-2.6.38-13-generic-pae
Found memtest86 + image:/boot/memtest86 +. Bin
Found Windows 8 (loader) on/dev/sda1
Done