It’s a bit of both. Not sure if some sort of Domain Mapping or Forwarding can be set up, WP.COM has some nice tools for those moving off their site to WP.ORG self hosted sites. Worth a look at them, can’t remember all the fine print.
You could put a static opening page that says “I have moved new address” and have a click on link to your new site. I think what you want to do is not have a “can’t get there from here” type message an have people need to go back and try other Google links. I would not delete the old site if you have taken all the content off it.
If a non-existent Post is tried visitors will get a “not found” message – so make the new page with a title of “I have moved” and have it the only page – then when the not found comes up visitors can look up on the screen and see the I have moved page click on it and then be given new address info.
Google will soon figure out that the old content is not there, but some sites it does not visit often. so patience grasshopper.
Google Webmaster tools also has a “change of address” feature to help when URL’s change. Worth looking at that also, no cost.
Hope some of this makes a bit of sense.
Good luck
Thanks for all the good suggestions but now I have completely screwed up both the old and new site and have no idea how to remedy this. I can no longer add or subtract anything from the old and when I try to add to the new it brings up the old (now defunct) page.
Glad you’re amused, but can anyone tell me if there is some way to completely delete both sites, wait a few weeks and then start over from scratch?