Best place to define combo boxes in Access

So, this is a general question about best practices for building Access solutions. I'm building a new system. In the past, when I've built "main" tables that have lookup fields, I always used the Lookup Wizard on the field type and associated the field with the lookup table right in the table design. But I was wondering what you experts think about that. Should you leave the field as Numeric and design the drop down only on the forms? Does it matter? Is there a speed or index issue?

Let me know your thoughts.

Thanks,
Eddie