Whilst the above can be made to work, the simplest way to do this is to make the Linux disk the boot disk in the BIOS.
At this point, Win2k becomes unbootable.
Update (at the bottom
, after the comments) the Ubuntu grub.conf with something like
map (hd0) (hd1)
map (hd1) (hd0)
This presumes Win2k is on the first partition. If there is a vendor recovery partition, try "root (hd1,1)".