EDIT (somewhere 00h30 UTC) : it seems it's back ;-)
There is an update that's being gone on the windows.php.net server ; see this tweet from @PierreJoye :
doing a major update of wiki and
windows.php.net box. Pls stop to bomb
mails everyone :)
about 5 hours
ago
For the "When windows.php.net is expected to be up?" part : well, when the update is finished, I'd say ^^
For an alternate download location... Sorry, I have no idea -- the server should come back at some point...
Can you wait a couple of hours ?
If yes, I'd recommend waiting until the official download location comes back on.