This question may be difficult to answer because it appears you may be installing/booting DSL ot Pupply inside a Fat partition, of an existing operating system, which both distros supports.
This is a Live CD implementation very much like opening a hot dog stall at the corner of a street. After exiting the Linux everything is rolled back to a single file and stored away inside the partition just like the hot dog stall finishes the day and goes home, leaving the street empty. In such a case the size of DSL or Puppy is exactly its iso file size, or slightly larger, like 50Mb and 100Mb respectively.
If you install either system formally in a partition then the size can be at least 3 to 4 times larger but that is within the partition and has nothing to do with other operating systems. In a formal installation all system settings are automatically saved whereas in a Live CD installation the distro does not save the settings by default.
In a Live CD installation you have not installed it. You just run it as a new Live CD every time.
DSL and Puppy are so small that the Linux filing system is held in the memory and not in a hard disk. That is why it can be compressed back into a single file and stored in a non-Linux partition. In a formal installation you store the actual Linux filing system permanently.
I would give DSL 500Mb and Puppy 1Gb for a partition to reside in. The partition will get filled up only if you leave data there but you can always move the data to another partition (call drive in XP).
You need "unallocated" hard disk space to create partitions.