FCE 3.5 is best suited for DV cams (for standard def) and HDV tape cams (for hi-def).
If you get a flash-based camera or hard drive camera, like the AVCHD hi-def cameras, you'll really need to upgrade to FCE 4.0 (not free) and then update 4.0 to 4.0.1 (free).
Unless I miss my mark, if you get the newer flash-based cameras that shoot only in standard-def (MPEG-2 format), or any of the small DVD cameras, that won't be compatible with FCE (any version) out of the box, but if the files are copied to the Mac and converted to a QT file with a DV codec, FCE 3.5 will work with them.