Using a "Refresh" directive from an HTML document is evil: it makes going back difficult, and a robot would have a hard time knowing that the document is intended as a redirection.
Raz' suggestion is good, though I would use a 307 status code for the redirect, since it's pretty clear from our above posting that it's a temporary measure.
I'm not sure exactly what action Apache would take with the DirectoryIndex directive given such a value, though.
(Aside: The 302 status code is more common in these kinds of circumstances, but I believe 307 is more proper in this particular case. According to HTTP/1.1, the only difference in semantics between 302 and 307 is that 307 redirections are expected to be handled with the same request method as the original request, whereas 302 is ambiguous. Me being the stickler I am, though, have come to the conclusion that 302 should be used in cases where a document will -always- be located somewhere other than the original request, but not always the same place (eg. /news/ may redirect to /news/jan/ one month and /news/feb/ the next); and 307 is used in such cases where a document is simply elsewhere for the time being, but will be returning to its original location (as seems to be the case here). Of course, this conclusion is based solely on the advisory names of the statuses ("Found" and "Temporary Redirect" respectively) and otherwise has very little basis in reality. )