1. Keep the current MBR unchanged, under the WinXP with the Division magician PQ Partition for Ubuntu.
2. To download the grub for DOS, the latest version cannot be downloaded because the latest version does not support the NTFS file system, and my WinXP is mounted under the NTFS system.
3. Add a boot entry for grub to the C:\boot.ini.
4. Download the Ubuntu 9.04 LiveCD, extract the Vmlinuz and initrd.gz under the Casper folder, and the entire. Disk folder.
5. Add a boot entry to the grub's menu.lst, pointing to the extracted Linux kernel.
6. Reboot the machine, enter GRUB in the WIN's boot menu, and enter the Linux installation ISO in the Grub boot menu
7. Start installing Ubuntu, in step seventh, install the boot manager in the Sdax (Linux-installed partition) instead of the hd0, or it will destroy the MBR, so that a single key restore function will disappear.
8. Re-enter the LiveCD temporary system and find out how to boot to the official Ubuntu OS kernel in the/boot/grub/menu.lst file under Sdax, and put it in the grub for DOS Menu.lst.
9. Reboot the computer, enter grub in the WIN's boot menu, and find the formal Ubuntu entry in the Grub's boot menu.