this is a cool single-exe, stand-alone XLS viewer that doesn't require Microsoft Excel to be installed. Requires .NET 2 Framework though. this app can be set as an external viewer for a quick peek into XLS files. The program even allows copying from the cells but there is no menu for that, have to use the Control-C hotkey. I have tested with files created in Excel97, 2000 & 2003 and so far it works.
-> D/L Link