I am forced to use this heinous 2007 version for my clients. Apologies for
any negative personal opinions expressed due to extraordinary amount of
frustration this evening.

I've installed Excel (and Word) 2007 only and and left my 2003 install
intact. Currently using 2007 trial version.

All i want is to have Excel 2007 open xlsm files only (e.g., office 2007
opens 2007 files, period) while having older xls files default to being
opened by Excel 2003 (and older .doc files opened by Word 2003, etc.). No
matter what I do to change the File Types settings, it continually defaults
to 2007 even through Windows (XP) tells me I have customized these settings.

I assume (HOPE) this has to (can!) be changed in the registry somewhere.
Does anyone know how/where? Please help -- this is driving me MAD!!! 95% of
my files are xls and going to stay that way for a long time to come, and I
cannot work efficiently with the lack of customizability of 2007. Sorry,
Microsoft, a single customizable toolbar does not even come close.

Thank you anyone who has any info!!!