I'm new to Linux. I tried installing the Backtrack and i reached upto partition manger. I have already installed Windows 7 in my system. I have drive d:\ (from windows) which has 150 GB and i used only 33 MB in it. When Linux detected the hard disk and i choose the manual partition and selected this drive and allocated 100 GB fto install Linux. In the Linux partition manager it shows 'unused'. When I click forward button it gives me an error "No root file system is defined. Please correct this from partitioning menu." Kindly help me on this.