All of the Parallel to USB Bridge devices/cables I've found are either intended to be used with a printer, or don't work on winXP/Win7
( usbgear.net/item_157.html, lpt2usb.net )
The problem is, I have a parallel port jtag debugger on WinXp and I don't have a parallel port! There's tons of USB to I/O solutions (Cypress, FTDI, etc), so I'm not sure why this isn't possible.
It would seem that if your usb adapter can read/write I/Os, not full speed since bit-banged, then it can generate EPP/ECP/SPP/BPP. Perhaps would the tricky part be the usb driver? It would have to intercept I/O read/write calls to 0x378 and route them instead to the DB25... But even this doesn't seem totally impossible... what am I missing?