The install cd should be able to do this for you..
Just pop it in, and in the install process, you'll see a step concerning partitions.
You can also use something like partition manager in Wind OS to format the drive, but keep in mind, that even if you did something like "format C:\" in the windows command prompt, you will still not have a good linux partition, which is why I'd recommend doing this via the installer.
Welcome to Vl,
I agree. The only thing I'd add to that is that AFAIK all versions of DOS and Windows need to be the first partition on your hard drive, so if you want to have both Vector and DOS / Windows 3.1 on your hard drive, you should install DOS first.
I'm also not sure whether a 16-bit version of DOS such as DOS 6.0 would install properly to a multi-gigabyte hard drive such as you've probably got (its limit is about 2 GB), but it's worth a try; if you do have a modern hard drive I'd be more inclined to install a modern 32-bit DOS which does cope with larger hard drives. Otherwise, maybe install DOS first and then try and install Vector over the remainder of the hard drive following the first 2GB by using a partition manager such as Partition Magic or gparted (which I believe is on the Vector live disk).
Anyway, as an old DOSer myself I'd be interested to see how you get on. Good luck.