First time poster so please excuse me if I have posted in the wrong section. I have searched but only came up with a couple unanswered threads where the poster did not provide enough info, so i will try not to do that.
I gave my grandfather my old desktop that runs windows 7 professional. He used to have an old computer that had XP on it. During the exchange I copied all of his documents onto an external hard drive and copied them to the new computer.
Some/Most of them will now not open. The windows 7 computer is equipped with office 2007. The documents that wont open are saved as .doc, .xls, .xlr.
My best guess is you somehow didn't install Excel when you installed Office 2007. If that is the case, click Control Panel --> Programs and Features --> Microsoft Office 2007 --> Change --> Add or Remove Features, and then check that Excel is selected as "Run all from my computer".
But assuming you do definitely have Office (including Excel) installed, try right mouse clicking the file in question, and then select Open With... (then select the button labelled the same again in the pop-up), and then click Browse and navigate to excel.exe (C:\Program Files\Microsoft Office\Office12\Excel.exe), and finally check-on "Always use the selected program to open this kind of file". That should work.
^Good advice, that. If Office has been properly installed with all of the various components, you should be able to open Excel files using the "Open with..." option and then setting Excel to always open this type of file.