Although this rewrite rule provides the desired results, I would actually suggest using a different approach:
It should be fairly trivial to write a PHP snippet that reads the values for module and tid, looks in your database for the relevant itemid value and then redirects using a 301 to the new url.
The reason that I suggest this is that it actually informs search engines that the page has been permenantly moved (301) to the new URL. It also presents the new url in a users browser address bar. Using the rewrite rule will show the old url in the browser address bar. The other advantage to this approach is that after a period of time (say 12-24 months), you could remove this code with little or no problems (as long as all links have been updated). Your rewrite rule solution will need to be a permenant fixture of your
website hosting to continue to satisfy the search engines.
If you really are happy with the previous proposed solution, then stick with it. But, IMHO, that would not be the best long term approach.
Hope that provides some food for thought.