How do we locate our attachment_fu photos in Windows XP?

Simply put: I don't understand the reasoning behind where photos are
stored in the :file_system option of attachment_fu?

  has_attachment :content_type => :image,
                    :storage => :file_system,
                    :max_size => 2.megabytes,
                    :resize_to => '320x200>',
                    :thumbnails => { :thumb => '100x100' },
                    :processor => 'rmagick'

  validates_as_attachment

  def full_filename(thumbnail = nil)
    file_system_path = (thumbnail ? thumbnail_class :
self).attachment_options[:path_prefix].to_s
    File.join(RAILS_ROOT, file_system_path,
thumbnail_name_for(thumbnail))
  end

For some 'magical' reason this worked fine with my Rails 1.2.6 source
code and now it objects. I am certain that the problem resides in
WHERE Windows XP tries to save the photo. I know this because I
changed the :storage value to S3 and the code went through (although
using Windows XP the image is not viewable using this plugin do to
some type of operating system anomoly?).
Anyway, how do you guys declare your "full_filename(thumbnail) path?

The error message I get with Windows XP is:
{"media_id"=>"6",
"commit"=>"Save Photo",
"mediaphoto"=>{"title"=>"Test photo",
"uploaded_data"=>#<File:C:/DOCUME~1/DAVIDK~1/LOCALS~1/Temp/
CGI4076-5>,
"geo_long"=>"0.0",
"show_geo"=>"1",
"geo_lat"=>"0.0"}}
I seem to recall months ago that there was a problem as Windows mixes
forward slashes with backward slashes??? I want the uploaded data to
put itself in the \mediaphoto\"goes here" folder.
Thank you,
Kathleen
KathysKode@gmail.com