I couldn't format my hardisk clean, there are always remaining of a few hundreds

you can format your hard disk by using the operating system cd...mostly windows xp is used as the operating system in the computer..boot your computer by inserting the xp cd and format all the drives of your computer... if this doesnt work then go for HIREN'S cd....in this cd you have lots of options to deal with your computer..go in recovery tools and erase the content of hard disk..empty the hard disk.... this options will definately help you.......