Just FYI if anyone is interested. My setup is as follows,
iBook G4
1.2GHZ
1.25GB RAM
ATI Mobility Radeon 9200 (32MB)
Dell 2407FWP
I can push the full 1920x1200 res @ 60hz/millions with spanning. Seems to work pretty well.
Only thing that bothers me is that the dock stays on the iBook. I did not enable clamshell (as I had no use for it).