You absolutely do make sense. First you want to backup the data that you want to keep(to another partition or to dvdrom), then, you can run a program, I like to use cfdisk, to delete the partition and make 2 new ones.
This if funny because this is actually something I'm in the process of doing myself. Except that in my case I am formatting hda1 (currently holding Breezy); I have to do this out of necessity for school and Windows 2000
Of course I'll still have Zenwalk on a reiser4 hda5, /home on hda6, Slack on hda7, etc.
To keep things fun I like to boot these various distros using different media. Some OS's boot from floppy's, other from GRUB in the MBR.
Good luck and have fun!