It seems Ubuntu 9.04 or lower does not recognized Windows 7 partition, perhaps Microsoft rewrite it or something to prevent this kind of setup?? :(

Anyways here is a workaround for it.

1. Partition the Disk using Ubuntu 9.04 CD. There are two ways to accomplish it, 1) using fdisk or 2) using gparted in which you have to run the Ubuntu 9.04 CD with Live Session option

2. Assuming you followed the option 2 above... Open a terminal and run gParted

>sudo gparted

 

3. Create an NTFS partition with your desired disk size.

4. Quit GParted and reboot

5. Boot up with Windows 7 RC DVD

6. When asked where to install, select the NTFS partition you created in step# 3 and click Next

7. Let windows 7 finish the installation

8. After Windows 7 is installed, bootup using the Ubuntu 9.04 CD again and proceed with the installation as usual to the empty partition

9. Ubuntu should now see the Windows 7 partition as a Windows Vista partition. We can now proceed with the dual boot!

10. Complete the Ubuntu installation and use Grub loader as boot manager and then restart your computer.