You can view multiple workbooks at once in a single instance of Excel by
choosing Arrange All in the Window group on the View tab in '07 or Arrange...
from the Window Menu in previous versions.
If you often work with the same two or more worksheets open, once you have
them open and arranged the way you want them, you can save your workspace,
which is basically just a list of the workbooks you want to open and how you
want them arranged. Opening the workspace would them open all of the
workbooks included when you created the workspace, arranged in the window in
the same way.
To save a workspace in 07, click Save Workspace in the Window group of the
View tab. In earlier versions, choose Save Workspace from the File menu.

"Becky Thames-Simmons" wrote:

I'd love to be able to view more than one Excel window at a time because it
would really help in my work requirements and tasks, but even though I may
have 2 or more spreadsheets open, as proven by my taskbar, I can't view more
than one. They both occupy the same "space".

It seems to me that there must be a way around this. I can't be the first
person to need to view more than one spreadsheet simultaneously. Does anyone
know a solution that I am missing?