On Windows XP we can view the offline pinned files as follows. 
- Open Offline files tab in Folder options windows(For detailed steps see the first part of the post How to enable offline files in Windows XP)
- Now in the Offline Files tab you can see a button View Files. See the snapshot below.
- Click on this button. It will open up Offline Files folder where you can see all the files that are pinned for offline availability.