Not sure if this is the right category but here goes...
We are in the process of switching from MovableType to a new CMS (expression engine).
The problem is that this new system is not compatible with the old urls for our articles. My fear is that when this new system is put in place we will lose all of the backlinks we have acquired, which are pointing at individual articles, thereby losing some of our search engine "weight". We will also likely loose traffic due to people clicking on links that lead to dead pages.
My question is this: How can we somehow create 301 redirects for all of our existing articles (there are several thousand) so that we don't lose all of those existing backlinks, which are pointing to MovableType urls that no longer exist?
If you change URLs you certainly will lose all that back-link-love. It's best not to change the URLs at all, but if you have no other choice then setup a 301 redirection scheme.
A simple way to do this is to use something like Xenu to spider your site and list out all of your current links. Then use a spreadsheet and make a table of the relevant redirects to the new URLs. Then apply the list to your .htaccess file.
Your SE rankings will most likely dip for a while with a URL change. It may take a while to recover. It may be good to budget for some extra promotion during this time.