I presume you mean Crop, which isn't quite the same as resize. If you haven't done anything else with the clips you can crop the first one, copy it, select the rest, and paste event attributes. This will copy whatever settings you have on the first clip to all the others.
If they are all the same size and require the same 'Resize' you can do your 'Crop' at the Track level so that any clip you add to that track jumps to the size you need. Do this to as many tracks as your project needs.
You could 'Resize' your clips then Render them out to normal DV (720x480) to edit them if your system slows down from the Real-Time Cropping.
I have all sorts of scripts that do this sort of thing, but I'm not sure exactly what sort of re-sizing you are trying to do. If all you need to do is apply the same pan/crop ratio to the clips, you can simply copy one event and then "paste attributes." Of course, if you have already applied fX to events, then this may cause problems. Excalibur can do all of this, and lots more, if you want to go that route.