I finally got it working this way:
1- Use paths with single "/", forget whatever you've read any other site
2- The uploaded file is always named: "c:/windows/temp/php2" in PHP3 and "c:/windows/temp/php3" in PHP4
so the code to copy the uploaded file to the final folder could be something like this:
$upload_path="c:/temp/$userfile_name";
copy("c:/windows/temp/php2",$upload_path);
this way you get the file in the path you want with the original filename.
