In addition to what Idle already told you, there is a way of accessing the book storage memory of OpenInpot with a WinXP PC. But first, I would not reccomend using the 0.1 version of OpenInkpot because it is missing a lot of features, and I think that what I am going to describe can only be done in later versions. You can get the 20090326 snapshot
here along with it's User Guide and Installation Guide. There are even later versions than that, but they do not yet have a User Guide or Installation Guide.
The User Guide links you to instructions on setting up an SSH connection between your PC and OpenInkpot. That will give you a command line interface that you can use to access the book storage area on OpenInkpot. However, you can go a step further and install WinSCP on your PC to have a drag and drop GUI to install or remove books from OpenInkpot's book storage area with simple Windows mouse point and click commands. You can get the free WinSCP
here. Once that is installed and setup you will have a book management method quite similar to what you are probably already used to. The book storage area in OpenInkpot is in /mnt/storage and you can set up whatever directory structure that you would like in that area.