Using HD captures in Premiere Pro CS3

I apologize if this has been covered; I scoured the forums and didn't find it. Also, thanks in advance to any and all who read this!

I've slowly but surely gotten the people I'm working with/for onboard with investing in decent creative tools, from getting the CS3 software (Windows) to now buying a respectable HD camcorder (Canon HV20). Here's my problem: I SEEM to be able to capture HD in Adobe Premiere Pro CS3 (though the preview doesn't work for me, but evidently that's a problem for many), and seem to be able to export it fine as well. The problem comes in editing it: I can't get the source monitor or playback monitor in PPro to show the video in its HD form while editing. Instead, I get what looks like a zoomed-in version of the footage, with mild choppiness when playing. This may be a settings-issue, but I've tweaked everything I know how to tweak, and still can't get what I need.

Is anyone familiar with this situation and how to resolve it? I'm sorry I sound like an idiot; that's what I am. Any insight at all will be much appreciated - thanks!