Should I use an inline varchar(max) column or store it in a separate table?

Question

I want to create a table in MS SQL Server 2005 to record details of certain system operations. As you can see from the table design below, every column apart from Deta

Answer 1

Having a nullable column costs 2 bytes for every 16 of them. If this is the only (or 17th, or 33nd, etc) nullable column in the table, it will cost you 2 bytes per row, otherwise nothing.