R300 will not print in vista: HURRAH! workaround
Though this thread looks too old, I would like to ask TaTu whether you were able to solve your problem or not. I was facing the same on my Vista and here is how I managed to fix it. I found drivers for Epson R220 for Vista SP1 32bit OS, and simply installed it on my Vista where I need to run Epson R300. There was no problem with the driver installation neither with the test prints. I just got a warning saying Wrong Device but we just need to ignore it and everything works fine.