I don't use the wacom mouse either. The tablet can be in pen mode, where each point on the tablet corresponds to the same point on the screen at all times, or in mouse mode, where I can lift the pen off the tablet and put it back somewhere else and I'm still pointing at the same point on screen - like I can do with a mouse. "Mouse mode" just doesn't seem to work well with the Gimp, it's like it keeps thinking I'm in pen mode, so I'm drawing somewhere where my cursor isn't pointing. Could be my config of old tablet and Vista, tho, haven't dug too deep into the issue.