OK. Firstly, your swap partition (hda3) should be fine as is.
Knoppix should detect it (AFAIK..).

If hda5 is 10GB you should be ok IF you split it in half (hda5=5GB/hda6=5GB) use qtparted.
Doing this means your current Linux install can be left alone. As hda5 (my hda1) hda6 (my hda3).
Alternatively, if you want to use your hda4 linux then hda5 can be left as is. So hda4(my hda1) and hda5 (my hda3).
ok?