You're going to hear it over and over here, but take a look at Kinkless GTD :
http://kinkless.com/. It's a set up applescripts set up to make GTD work great with OmniOutliner, and it synchronizes with iCal, which will then sync down to your palm.... I'm using it with my Tungsten T3 and it works great (though I am using MarkSpace's Missing Sync to sync with ical...)
George