Hi,
This is the default behaviour for most browsers, and I'm not sure it that can be changed, AFAIK.
I use Safari and each new window is stacked just a little to the right and just a little lower than the one before. This lets you see how many windows are open in the application and to be honest, I just enable Tabs and use them instead. It's very rare that I open up a new window but I also have a 20" screen too!
Make sure the top of the original window sits flush with the Finder MenuBar and this should help a bit. You can also set the Dock to Always Hide in Dock Prefs to free up screen real estate, or relocate it to either side of your Desktop.