I've installed the Office 2010 Beta, but I have some programs that aren't compatible so I have 2007 installed. 2003 is also installed for testing purposes. Right now, when I open an Excel file, it opens in 2010. Any way to set Excel 2007 as the default when opening Excel files?
You don't say what OS you have, so your mileage may vary. On XP, the usual way used to be from the command line:
However, on my Win7 system this makes no difference. (like you I have 2003, 2007 and 2010 installed, 2007 is default for me and does not change with above commands, run as user and as admin) Next best option usually is control panel > programs > add/remove (again exact route depends on your OS here) > choose the Office install you want and do a change > repair on it. This can take a while, but I just did it on 2010 and it worked, this is now my default.
With the benefit of hindsight, install the one you want to be default last, repair effectively winds back the clock and installs a previous one again, making it "last".
(have to go run it on 2007 now since that is what I really want to be default for Excel at the moment since I am teaching some courses on it next week)