Software

I have Excel 2007 installed on my computer. When I open a .xls document with Excel 2007 and do a Save > As and save the document with a new file name (still using the .xls file format) Excel will create the new .xls file as it should, however it modifies the time stamp of the original file to match the one that I just saved. I tried this with Word 2007 and this does not happen. Does anyone have a solution to this?