[newbie] why formatting is done each time Mandrake is installed ?how to skip it?

[Bill Crompton]

I have installed Mandriva twice on my hdd.since i am a newbie,i like a fresh start each since i mess up things by my R&D!
I have seen each time i install mandriva it reformats the drive.why does this repeated when my partition is of ext2 linux type.is their any way we can avoid it?i am going to install mandriva2006 soon.my computer vendor has adviced against frequent reformats as its not healthy for the drive.
any suggestions?

also tell me how do i scandisk and defragment the drive?
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bill crompton