Yes, it's the very top option I believe, which is "Upgrade." I think the other two options are "Archive and Install" and "Clean Installation."
I think the verbage says something to the effect of "Upgrade a previous installation of OS X."
You can boot from the Panther install CD and go up to the point where you select what type of installation you want (upgrade, clean, etc.) without actually changing the disk at all, so no damage will be done if you wanna check. You can always quit the installer at this point and go back to your regular install.