Just like Access 2000, 2002 and 2003, Access 2007 cannot modify an Access 97
MDB file. You need to convert it to at least a 2000 version MDB to develop
it further in Access 2007.
And naturally enough, Access 97 cannot use the 2000-version MDB file.
You can use both A97 and A2007 on the same computer, provided you do a
custom install. (The default install removes previous versions.) The main
reason for wanting to do that would be if you were a developer who still has
to support software writting in A97 for users who only have the old version.
If you are considering converting your A97 MDB files to a later version,
this may be useful:
Converting from Access 97 to 2000 and later
at:
http://allenbrowne.com/ser-48.html
If you are considering going straight to A2007, see:
Converting to Access 2007
at:
http://allenbrowne.com/Access2007.html