Hold the CTRL button while rolling the wheel.
Rolling the wheel by itself scrolls up and down.
If you hold the SHIFT button while rolling the wheel, the screen will scroll left and right.
Hitting "Insert" will pan towards the cursor, as will clicking the middle button/wheel.
Holding the middle button/wheel and moving the mouse will zoom in and out, depending which direction you drag the cursor. Dragging down zooms out, dragging up zooms in.
"Page Up" zooms in, "Page Down" zooms out.
Hitting "Home" zooms to extents of the visible image in Logic, to the extents of the board outline in Layout.
Added after 15 minutes:
Oh, the ghost image. That artifact comes and goes with releases for some reason. Annoying, but harmless.
FYI, the "End" key refreshes the screen.
I mentioned this in another post (look for "New to Pads 2007.4"), but there's a list of modeless commands in "Help". Get that and print it out. very useful until you get a handle on them.