Copying a disk

[Hadders]

Hi all,
  I have an old hard disk with a copy of Redhat 9 on it.

I don't want to change anything, but instead want to migrate this to a 
new disk and have it coexist with Ubuntu and Windows (maybe).

I figure I can boot up a rescue CD and partition the new disk.

Then how do I copy the old partitions from the old disk?

Do I simply mount each partition and copy the contents to the new one?
OR
Do I use 'dd' to dump the contents across? Would this require a direct 
size for copying purposes?

Thanks in advance for any help.

H