Vista - Vista Business Complete PC Backup Question

I know the following question is kind of silly but asking never hurts... (at least so they say ).

I tried to do a complete PC backup using Windows build in "Back up Computer".

The next screen that pops is the one where I have to select the drive I want to save the backup image.

So my question is the following:

If I choose to save that backup image that Windows is about to create to my second partition (The same physical drive the boot/system partition is - I know its not recommended), will I loose any data that is already on that partition?

Like i said, I know it's a silly one but I was just wondering since the wizard only gives me the option to select the drive and not a specific location I want to save it in.

Thanks in advance,
jimmy.