You should convert it to a newer version to avoid issues with the newer JET engines. The only problem you might have is if the database is still being used by another older version.

If that is the case do the following:

Create a new empty database (2000, 2002, 2003, does not matter)
Link all the tables from the old database
Do all your processing thru the newer database. This should treat all the tables as if they were in the newer version.

Keep in mind that all the versions of Access have the same size limit, and if the error you are getting is related to DB size, you might need to repair/compress the DB. If the DB is larger than 500MB, break the table accros multiple MDBs and create one MDB that links them all.