The file you exported from FCP is squeezed. If you encode it with Compressor and make a DVD with DVDSP and tell DVDSP that the file is 16:9, your DVD will play 16:9.
If the QT file is the final product and needs to play 16:9 you can open the file with QT Player (PRO) and export it changing the Aspect Ratio choice in Options to 16:9. You can also do this out of FCP by using Export > Using QT Conversion by opening Options and in the Video Settings select Aspect of 16:9.
John
MacPro 8-core 2.8GHz 8 GB RAM OS 10.5.5 QT7.5.5 Kona 3 Dual Cinema 23 ATI Radeon HD 3870
ATTO ExpressSAS R380 RAID Adapter, PDE Enclosure with 8-drive 6TB RAID 5
24″ TV-Logic Monitor
Final Cut Studio 2 (up to date)
Pro Tools HD w SYNC IO, Yamaha DM1000, Millennia Media HV-3C, Neumann U87, Schoeps Mk41 mics, Genelec Monitors, PrimaLT ISDN