I am interested in adding additional fields and relating them to users of a portal. For instace, I would like to add properties such as account #, identifying codes, balance, or any number of additional fields.

Is there any documentation or any modules that would allow me to do so? So far I was thinking I would create and additional table in the db and relate its rows via userID or something like that, but then I start to think about the process of deletion or updating and I get worried. I did notice an module project named UDT (User Defined Table Module)... is that something I could use?

Thanks in advance for any help. BTW, I am using DNN 4.3.5 with SQL Server 2005 Full ed

did you check out http://www.dotnetnuke.com/Community/Blogs/tabid/825/EntryID/479/Default.aspx?