I find it annoying that VS 2005 opens the Forms editor when you double-click on a source file for a form. Dammit Jim, I'm a programmer! I want to see the code. I searched high and low for a registry setting to change this but to no avail. Certainly there must be a way to change this. Then a colleague pointed out simple way. Right-click on the source file and select "Open with..." You'll get the following dialog.
Select the code editor and click "Set as Default". Couldn't be easier.