The uploadprogress extension for PHP never really worked on Windows and since I don't have a Windows development environment I could never do a proper analysis of the problem. Until this week, when Tomas Holusa sent me an email telling me about some VCWD_RENAME problems on Windows. I digged a little bit deeper and found this patch commited by Pierre 10 months ago to the PHP 5.3 branch. This confirmed the problem that if the target file already exists, VCWD_RENAME fails on Windows (but works on unixy systems). Writing a patch for that problem was then easy and according to Tomas, the extension finally works on Windows.
If you want to try it out, Pierre was so kind to compile the latest CVS snapshots for PHP 5.2: php_uploadprogress-1.0.0-5.2-Win32-VC6-x86.zip or php_uploadprogress-1.0.0-5.2-nts-Win32-VC6-x86.zip (or search for it at downloads.php.net/pierre). More feedback of running this on Windows would be appreciated, then I can finally release uploadprogress 1.0.0 and mark it as “stable” :)
Btw, I still owe you a “Caveats with Upload Progress Meter” for the most common problems with the extensions. I didn't forget that and can hopefully post it soon.
Update: Fixed the link to point to the 1.0.0 DLLs