I already got windows 7 installed on my laptop with 3 drives C: D: E: and I also wanted to install Ubuntu on the same drive C: and make it a dual boot. How to do it ? is it possible ?
And will I lose the data on other drives i.e D: E:
It is possible and I think you won't lose your data on D: and E:, but your Win7 installiation may become corrupted, so you should back up your files. You have to partition your C: drive and because of that you can lose your data. When you are using the Ubuntu Installation wizard you will be asked what to do (install over win7 or besides or something else), there you choose do something else and than you have to shrink the Windows 7 partition on your C: drive. Than you can create the filesystem needed for Ubuntu on your new free space on C:. The installation wizard should automatically detect windows 7 and enable dual boot.