It's definitely something that can be done... it's how my D600 works right now. I didn't do anything explicit to make that happen, but my system is imaged from our corporate desktop configuration so perhaps something was configured in the base image for me.

All it is basically is using hardware profiles. Go to 'My Computer' properties, then the 'Hardware' tab. Click the 'Hardware Profiles' button. You should have two profiles listed, 'Docked Profile' and 'Undocked normal'. They may be named somewhat differently on your system. If you only have one profile then you need to create another one. If you have both, then check the properties to make sure one is indeed set for the docked state and the other is for the undocked state. Boot up undocked. Check which profile is used. Set your resolution appropriately. Now boot up while docked. Check which profile is used. Set your docked resolution. If the system is correctly recognizing the docked state and choosing the correct profile then your resolutions should switch automatically each time you boot. This even works when hibernating and resuming from hibernation in the alternate state. I do this all the time... hibernate while undocked and then resume in the dock, and vice-versa. The resolution switches just fine.

If things aren't working as described then I guess you'll have to do some troubleshooting into the situation. Make sure you have all appropriate Dell-supplied device drivers installed. You can also tell windows to let you choose the hardware profile at boot time so you can make sure you're using the correct profile.

Good luck,
Rob