Excel work sheet how to i open

Hello,

When i am trying to open an exel sheet saved from windows 7 platforms, i am unable to open in windows xp plantform. the file that i was copied into a spycam pen drive, the same file i am unable to open, the messages is as follows:

Excel cannot open the file name.xslx because the file format and the file extension is not valid. Verify that the file has not been corrupeted and that the file extension matches the format of the file.

The above massage is showing , please let me know the problem and help me to open the file.