How can I access my Photostream on Windows?
On a Windows system you can access Photo Stream by installing iCloud Control Panel for Windows.

Based on the description it allows you to access all the features within iCloud. Though this is only supported in Vista and Windows 7.


  The iCloud Control Panel is required to use Photo Stream, Mail,
  Contacts and Calendars (Microsoft Outlook 2007 or later required) and
  Bookmarks (Safari 5.1.1 or Internet Explorer 8 or later required).