I'm fairly familiar with generating xml mapping files and class from db schemas when it comes to using ORM and other code generators, howver i've heard that this is bad practive since the db is relational and cannot reflect behaviour like objects. So if this is true and I would love to hear any other thoughts on this, is there some way of being able to auto-generate a db schema, (tables and relationships in sql server 2000) based of the relationships that are setup in the xml mapping files. I reckon this would be amazing if possible since then it would remove this whole debate. I could develop my objects first, create the relationships and have a db schema created for me..

Any insights would be greatly appreciated.

Use NHibernate.Mapping.Attributes and SchemaExport...
(read: http://nhibernate.sourceforge.net/nh-docs/html/NHibernate.Mapping.Attributes.html)