After over a year of using MS Office 2010 (a couple months in Beta, and now the RTM), and several years of using 2007, I have become really frustrated with Excel opening in the same instance. This “feature” was implemented in Office 2007 to save memory, and is a great feature if you are working on alike notebooks. I have two monitors and often like to compare my notebooks side-by-side, and I can’t believe I have ignored this problem as long as I have – but I now have a solution!
This fix works by adding certain keys into your registry. It will not only allow you to double-click on an icon and have it open in a seperate window, but also adds a neat little Right Click dialog that reads “Open in New Excel Instance”.
The following link is for Office 2010. To apply the fix, download the .zip file below and open the .txt file, save it as a .reg file and run it. If you want it to work with Office 2007, just find and replace the words “Office14″ with “Office12″ and it should work the same. If you are running a 32 bit version of Office on a 64 bit Operating System (Office is installed in C:\Program Files (x86)\Microsoft Office) then make those changes and it should work the same as well.
A special thanks to the original author of this fix. His post is aimed more at Excel 2007 and 32 bit XP and is located here.