… you are using interlaced material and

- you notice the single-field processing of DV-material ('standard') or 

… you notice loss of color on export or 

… you notice loss of detail on export of HiDef-content

follow these steps:

Step 1) 

Import your content into a new Event.

Step 2)

ctrl-click on clip, 'Reveal Clip in Finder'

Step 3) 

drag that mov into JES Deinterlacer

let the Gamma set to 2.2 
Project is 'Deinterlace' and the magic is done by 'both': each field gets a frame; JESDI doubles the frame-rate automatically, from 60i (=30p) to 60p .. 
in the Output-Tab, save to Desktop, Direct/AIC, Sound Export/Copy sound .. 

note: the conversion increases file size by approx. 50%! video eats disk space ... ;)


In iMovie09, choose 'Import Movie' and choose THAT file to be added to your Event.
You can now erase the original file.. 

that's all, Folks!

NO 'bad' effects.
NO loss of fields.
NO loss of 'data'.

On 'Export Movie', iM will downsample back to 30/25fps. 
On 'Export using QT', you can choose 30/25i or 30/25p for FullHd export (for usage with a WD TV HD