I've been using ES almost exclusively with SQL Server 2005, but I have a module that must use an existing access db.

I have no problem reading.  I do have a problem with inserts.  I tried to add a record using standard ES syntax.  When the code runs, no record is added, no exceptions are thrown, the code just acts like it worked.  Except looking at the table, no record is added.  The access db has a primary field that is a Guid.  When I tried it as autoinc, it worked as expected.
 

MailingListCollection mlc = new MailingListCollection();
MailingList ml = mlc.AddNew();
ml.Person = tbName.Text;
ml.Email = tbEmail.Text;
mlc.Save();

MS Access has two types of AutoNumber fields, Replication Id (Guid), and Long Integer. EntitySpaces currently only supports Long Integer for AutoIncrements. As a work-around, if you need the Guid primary key, you will have to manually open the generated class. Scroll down to the table's Metadata class constructor, and change "c.IsAutoIncrement = true;" to "c.IsAutoIncrement = false;". Then, add the following AddNew() override to the custom entity class, where "GuidKey" is the name of the PK field:

namespace BusinessObjects
{
    public partial class Table1 : esTable1
	{
        public override void AddNew()
        {
            base.AddNew();
            this.GuidKey = System.Guid.NewGuid();
        }
    }
}