Pxl files & other pocket version files from the desktop

Hello,
In earlier versions of Windows I could simply open pxl files from the desktop using Excel & Word and the files opened and could be worked on without any problem. Now with Windows 7 when you attempt to do this you are asked to associate the files with a program - the options offered do not include Excel. So the files are perfectly useless. Any ideas on how to open them using regular Office programs
Rick