Final Cut Pro 3 is obviously much better and in my honest opinion, you can learn it just as quickly, but if you're new to NLE then stick with iMovie 2 for now. Here is what you are looking for:
From iMovie 2 to ALAMDV2:
1) In iMovie, select "File", Export
2) From the Dropdown menu select "To Quicktime"
3) From there, select "Custom" Settings
4) Select a frame size of 640x480. Under Video Compressor, select "None", Number of Frames should be set to 29.97 fps (unless you're in Europe using PAL, which is 25 fps)
5) You can turn Audio Compression off as well becuase ALAMDV2 doesn't read Audio, only Video (you need to "Extract Audio from Clip" inside iMovie2 before you export to presevre the audio from your clip)
6) Export your clip onto your Desktop
7) Open ALAMDV2 and locate the Quicktime clip you just exported, import it (Standard Import)
From ALAMDV2 to iMovie2:
1) Select Export
2) Export to Quicktime using the same settings you used in iMovie2 (640x480, No Video Compression, 29.97 fps or 25 fps PAL)
3) Open the exported clip in Quicktime Pro 5 and select "File", "Export" (convert it). You need to change the file type to DV Stream. iMovie's major shortcoming is that it won't read ANYTHING except DV files.
4) Open iMovie2 and select "File", "Import" and import the DV Stream file you just exported from Quicktime (confused yet
5) You will need to "Park" the clip on the Timeline in iMovie2 above the Audio you "extracted" from the original clip (select "Lock Audio at Playhead" from one of the dropdown menus)
That's it. Good luck.