There are two different ways in QuarkXPress to view the contents of a picture box as you drag the box on the page:
Click and hold the mouse for a couple of seconds.
The mouse pointer will change.
(Note, the mouse pointer will not change in QuarkXPress 8)
Drag the picture box to the new position, and the box contents will display as the box is dragged to its new position.
If the two seconds is too long a delay period, you can change the delay value:
Go to QuarkXPress > Preferences (Mac), or Edit > Preferences (Windows).
In the Input Settings pane set the Delay Before Live Refresh Drag value to a lower number. The range allowed is 0.1 to 5 seconds.