Win2K/XP multiboot

I have bought a new harddrive with 500GB for making a multiboot with Win2K/XP.
I created a MsDos partition-table since it's default and recomended.
I made 2 primary partitions for the systems and installed Windows2000 on the
first.
When it had formated and placed the files for installing Win2K, I could not
boot the setup on the harddrive.
When I looked at the partitions in Ubuntu's partition editor, there was only
one 500GB partition who I did not allow the creation of. The other partitions
was gone.

How do I get both Windows2000 and WindowsXP on the same drive?