i have route 66 and it is ok, but it definately is CPU/harddrive hungry for some tasks like repainting the details on the map after you scroll. i use a keyspan serial to USB adapter and it works great once i got the correct drivers installed. I am on X.3.7 right now. I have used a garmin V and a garmin III plus with it. the only thing i have noticed is that at 4800 baud it was a bit more delayed then i was happy with. the III plus would only communicate at 4800 for the NMEA output. I did not check on the V.