Thanks for the replies, a few points to clarify I think. I do not think the USB port of the PSP needs to be powered in order transfer files. I think the USB OTG bridge is used to connect 2 USB "clients" (ie.both the Hi-MD and PSP are set in client mode), the Copy button on the USB OTG bridge being used to copy from the "donor" client (Hi-MD) to the "recipient" client (PSP). I know for a fact that PSP (at this point in time) & Hi-MD does not support USB host mode, thus the necessity of placing a "bridge" between 2 devices. If indeed the PSP in the future supports USB Host mode (there's talk of USB powered keyboards for the PSP being released which would necessitate some host capabilities?), then there would be no need for a USB OTG bridge? (although I doubt there's a mini type B to mini type B cable available that would allow me to connect the Hi-MD to the PSP directly) The cheap USB OTG bridges I have seen only have usually a "Copy Entire Disc" or "Copy root folder" functions. There are more expensive ones which have a LCD screen that allows folder or even individual file copy. My query is, would setting up the appropriate folders on the Hi-MD (eg. MUSIC) and loading it MP3 files, then using the Copy Entire Disc feature result in the folder and contents being added appropriately to the existing MUSIC folder in the PSP? Sorry if this sounds confusing! I have read somewhere that people have successfully transferred files from a Hard Disk USB OTG boxes to the PSP, just wondering if Hi-MD will do it as well.