How do I make .xls opened by Excel2003 and .xlsx opened by Excel2010?

[hill0093]

I have both Excel2010 and Excel2003 installed and cannot get them to open their own file.
It's just that I want them to do that. I have Windows 7 Home "Premium".
This is the way it should work (I believe):
Right click file having .xls ending.
Click open-with -> choose default program.
Click Microsft Excel2003 -> select Always use the selected program to open this kind of file.
Click OK.
Right click file having .xlsx ending.
Click open-with -> choose default program.
Click Microsft Excel2010 -> select Always use the selected program to open this kind of file.
Click OK.
But Microsft Excel2003 and Microsft Excel2010 are not distinguishable as separate programs.
How do I solve that?

 

[pbornemeier]

From Control Panel\All Control Panel Items\Programs and Features, select Excel 2003 (or Office 2003) installation and choose Repair.
This will register file associations for the 2003 programs "over" the later versions. If there is an update to Office 2010, you will have to re-repair 2003 since the Office 2010 update will overwrite your Repair that assigned the 2003 programs to .xls, .doc, .ppt
This worked for my setup. .xls opens with 2003; .xlsx, .xlsm opens with 2010.

More at this site titled:
Information about how to use Office 2010 suites and programs on a computer that is running another version of Office

which includes this illuminating paragraph:

Office files in Microsoft Windows Explorer
When you double-click an Office file in Windows Explorer to open the file, the following rules apply. Note These rules also apply when you double-click the Office file in the Recent Documents folder in Windows.

---If a version of the program in which the file was created is running on the computer, the file is opened in that version.
---For Office XP, if no version of the program in which the file was created is running on the computer, the file opens in the version of the program that you most recently installed.
---For Microsoft Access and for Microsoft Word, if no version of the program in which the file was created is running on the computer, the file is opened in the version of the program that was most recently started.
---To associate files with the programs that are included with a particular version of Office, run the Office Setup program, and then click Repair Office. When you do this, the file associations for that version of Office are registered.

Note You cannot use this method to register file associations in Word or in Access.

Note If you install a software update for a version of Office, the software update repairs that version of Office. You may have to repair some or all Office products after you install a software update to restore the file associations.