How to connect two Computers with USB? [duplicate]

There are two computers. The first one is the client, the second one is the server. The client needs access to some files on the server.

On the server it is possible for me to install any software (Ubuntu with root access). The client is WindowsXP and I cannot install anything. However there is an USB-port to which I can connect storage devices.

Is there a way (hardware and/or software) which I can use to connect the two computers with USB?

I could imagine a software for my server which uses USB to act as a simple storage device for the client connected to the other end of the USB cable.

USB is an asymmetrical, master-slave interface: there is one host controller that handles many devices. Host-controller is a bus master: it initiates all transfers on the bus, thus requesting a reply from addressed device on other side. A host controller cannot work in a slave mode, i.e. as a device (you can still have a host controller and device controller connected to same physical port; this is called USB OTG, but is present only in some printers, cameras and PDAs. AFAIK, there are no PC USB OTG controllers), and therefore you cannot directly connect two PC's with USB cable.

So you need a special 'cable' that is really a device which behaves as a device to two host controllers. They are not very expensive; this one should work fine.