Windows 7: Changing from Office 2003 to either 2007 or 2010

Since support is about to end for 2003 version, I think that it may be time to change. If I go to either 2007 or 2010 version, I think that I understand that "opening and reading" an "XLS" file will not be any problem since you can use the
Compatibility Pack". I am not so sure about the templates ( XLT ) files. Will I be able to continue those files, because I use them on a daily basis. Will an XLT file open and be able to be used in either 2007 or 2010 ?

XLS files can still be opened. Supposedly it is possible that some things might appear a little different when opening them with newer versions, but I've never found this to be true. And while I can't tell you for sure, I'm 98% sure XLT files will open just fine too. Basically you can open old format files in newer versions of Office, but you can't open newer format files with older Office versions.

I support what Slammer said, and if you want a one in all viewer for all your needs, visit this site:

Free document viewers for Office files: .doc, .docx, .xls, .xlsx, .odt, and more

Good luck

You may find this Microsoft Office article useful: Issues that you may encounter if the computer is not fully updated to be compatible with the Office Open XML formats