I've never used FCE, but if it's like FCP you should have an anamorphic (or widescreen or 16:9)button in Sequence Settings. With your sequence open go to the Sequence menu and choose Settings. If the anamorphic button is there check it. Hopefully that will turn the sequence into a 16:9 size. If FCE is like FCP, when you drag the first clip into a new sequence FCE asks you if you want the sequence to adopt the settings of that clip. If it's a 16:9 clip the sequence will be setup that way as well as matching the frame rate and other parameters of the clip.
MacPro 8-core 2.8GHz 8 GB RAM OS 10.5.8 QT7.6.4 Kona 3 Dual Cinema 23 ATI Radeon HD 3870, 24" TV-Logic Monitor, ATTO ExpressSAS R380 RAID Adapter, PDE enclosure with 8-drive 6TB RAID 5
FCS 3 (FCP 7.0.1, Motion 4.0.1, Comp 3.5.1, DVDSP 4.2.2, Color 1.5.1)
Pro Tools HD w SYNC IO & 192 Digital I/O, Yamaha DM1000, Millennia Media HV-3C, Neumann U87, Schoeps Mk41 mics, Genelec Monitors, PrimaLT ISDN