While installing Ubuntu I encountered following information on the screen: Allocate Drive Space Device Type Mount Point Format? Size Used /dev/sda /dev/sda1 Ntfs 104MB 35MB /dev/sda2 Ntfs 169505M 36529MB /dev/sda3 Ntfs 129487MB 73985MB /dev/sda5 Ntfs 20971MB 3221MB New Partition Task Add Change Delete Revert Boot Loader Device for boot loader installation: /dev/sda ATA WDC WD3200BEVT-7(320.1GB) /dev/sda1 Windows 7(loader) /dev/sda2 /dev/sda3 /dev/sda5 Question 1: Which one I must select?I selectet ?/dev/sda5? and ?/dev/sda ATA WDC WD3200BEVT-7(320.1GB)? option. And when I clicked on Install now button, an error window appeared with the following message: X No Root File System __ No Root File System is defined.Please correct this from the partitioning Menu. Question: Please help me from where I should correct this problem?

As I'm installing it along with Windows 7,tell me how to manually extract a 20 GB space from the Windows partition and then format it with some other file system I reckon ext3 or ext 4? If I'll choose other options they ask me to erase full HDD that I can't do as I have lot of data in my HDD.

You can use the Diskpart command to shrink you current Windows volume to free up space so that you can load the other operating system. DiskPart Command-Line Options http://technet.microsoft.com/en-us/library/cc766465(WS.10).aspx Visit: anITKB.com, an IT Knowledge Base.