It depends on what you wish to do with it.
My own preference, is to configure it into at least two partitions. The first, C: is used in the normal manner; operating system, applications etc, and the second is used for all my personal files. I also normally move my address book and such like to D: (or whatever the partition is set as).
If I then get a serious crash, and have to use an image to get the machine up and running again, all my personal data remains unscathed.