I was using V2007, but am not aware of any differences between the two
versions. I have access to V2003 and will try it.
As far as using project, it really depends. If you need to do planning as a
regular activity, probably. If doing Gantt charts is infrequent, and you
don't need all of the features/flexibility that Project provides, then, it
may not be worth the extra cost. Gantt charts isn't the main thrust of
Visio. I do them only on occassion, so, Visio is fine for me. Just the
basics, though.
Just for a sanity check. You might want to build a simple chart in Visio.
Verify that you can change the width without affecting the dates, then export
it to a file. (If nothing else, that will give you a template to compare to
the file you're importing.) Then, import the file, and see if everything
behaves as expected.
Wapperdude