How do you partition to install Vista?

I read the parts on like putting it on a flash drive, how do I partition the drive? Does Vista do it automatically for me when installing? What will happen to the data I have on the drive right now?

 

Vista will allow you to choose the drive and the partition on which to install itself.
At the same time, you will have the choice to manipulate the partition (delete,add, resize etc).
if you're installing on a partition, all the data on that same partition will be GONE.
if you have a single partition comprising the whole hard drive, all the contents of the hard drive will be GONE.

 

I did what seemed to be the most logical idea on my 120GB model. In XP, I shrunk its partition down to as small as possible, giving it about 900MB of free space, then installed Vista in the unpartitioned space. The Vista bootloader now gives me the option of what OS to boot into. If for any reason Vista goes bad, I can just easily boot back into the factory XP installation, and delete the Vista partition by re-expanding the XP partition.