hi .. are you using the PAL widescreen pre-set when you make a new comp? I’d say it’s just a setting for how you view it in FCP. Like on our machines, it still looks stretched on the computer monitor, but then all OK on a broadcast monitor …. maybe FCP has a Pixel Aspect Ratio Corrector like AE does… ?
maybe you can render out a test and see how it looks in QT? it should still look squished, but at least fill the whole 720×576 frame. or even better, burn a DVD and see how it looks on the TV.
oh, if you find that it is actually not filling the screen… in FCP under motion settings there is Distort->Aspect Ratio …. try adjusting this….
hope some of this rambling helps 🙂