In Windows 7, in most applications, when an application is maximized...I can "tear" the window (grab the title bar and drag) from it's maximized size and off the top of the screen and then I can drag it to wherever...but when Excel is maximized I do not have that functionality...Is there some trick to adding this functionality for Excel 2007...I can do it with Word 2007 so it doesn't appear to be Office itself. The machine is a Dell Latitude D820 with the Nvidia Quadro NVS 110M video card...running the latest video drivers...
It is apparently a known issue/bug: http://social.technet.microsoft.com/Forums/en-US/w7itproui/thread/ae500d79-1b19-4f8b-9983-926ba864c5c5
Here's the only way that I know how to in Windows 7; it's not the cleanest but works for what you want.
I followed the steps as said here: http://onlineitpro.com/?p=810
The only problem is that afterwards you can't double click on a speadsheet and open it. You'll have to open an instance of Excel and then open the file from there.
Hope this helps.
As for "Why" - the main Excel window is actually just a container for you worksheets. Below the main minimize, maximize and close buttons is another set of the same buttons. If you click the bottommost minimize button then only the active worksheet will be minimized, but not the whole Excel window. Probably that's why it doesn't behave the way other programs do.