Ultimately, it depends on what you are trying to accomplish. I think the majority of us would probably recommend just adding a PXE boot server as suggested by Thomas above.
I would definitely not recommend imaging across a WAN link though, especially if other data is sharing that bandwidth.
Regarding storing images locally, there are a few ways of handling that. Some people use PXE redirection, others use "getsrv" (I personally use getsrv), and others use home grown scripts.
There are reasons to add another DS server, and there are reasons not to. I would lean towards not having the additional server as it would mean one more administration point (as a sole administrator here, I don't need the additional work :D).