> NetBSD uses the whole disk (3 partitions, root, usr and swap). IDE is
> slow, and I have a SCSI2 disk that I would like to use instead.
> 
> What I'm wondering about now is: Can I just make 3 partitions on that
> disk, e.g.: root 200MB, swap 128MB, usr 4GB, make the repective
> filesystems on those partitions, and copy the OS with cp from onedisk to
> another, and throw away that IDE junk once and for all?
yes. but you need to
a) do installboot
b) don't forget to use -pR options for cp