When upload an image file with attachment_fu on windows, you will see there is an error such as 'Size is not included in the list' and you cannot upload the file to Amazon S3.
You can refer to the link "http://epirsch.blogspot.com/2008/01/fixing-attachmentfu-on-windows-like.html" to use attachment_fu_patch file but I cannot make it run because of lib path error.
Thus, I simply update the following three files and restart the server, which works great:
@tmpfile.fsync # added this line
f = File.new( temp_path )
(temp_path ? File.open(temp_path, "rb") : temp_data), # added , "rb"
:content_type => content_type,
:access => attachment_options[:s3_access]
@old_filename = nil