When you double click on a program then windows XP checks the file association to see which action to take. One of these action is to check a list with extensions which you can find under [Tools] [Folder option] [File types]
if you have ms office installed there will be several listen file extions here, e.g. `xslx'. (I got no access to computers with ms office atm. I am at home where I use open office. Hence more more precise screenshots).
If you click on an extension it should show which program it opens with, an option to change the program and a tab advanced.
Office programs seem to default to using DDE. Check if this is the case by going to [Advanced] and [Edit]
If the tick mark is not there you just found your problem. Mark it and test again. :)
If it is there and the problem is very recent, first check for the XDocCrypt.A/Dorifel virus (New since yesterday. Quite virulent and messing with both excel and word files).
Sometimes you run into situation where the DDE option is marked but does not work. Not even after de-installing and reinstalling office. I am not sure what causes that problem, but I have worked around that in the past by defining my own action via [New], selecting excel as the program to open it (use browse) and adding "%1" behind the program.
(If you do not add anything clicking on and .xlsx file will start Excel. it will not pass the file name and you will still look at an empty spreadsheet.
Adding %1 will pass the file name. It will work as long as the file name does not contain space. Else double clicking on
my test.xlsx will open excel and tell excel to try to open the file
my. Which will fail.
"%d" should work, even for files with spaces in them.
1) I used to use that with office 2003, not 2007. It should work the same though.
2) I am mostly recalling stuff I did 2 years ago. I might have skipped a step.
3) Fully untested with 2007 and xslx, since I do not have access to office 2007 atm.
Please let us know if it worked, or if I need to clarify some points.