<p>Does anyone know of any documentation by MS or someone else that lays out the best practices for developing a 3 tier architecture in ASP.NET.  I am in the process of trying to convince my boss that the current architecture needs rethought and reworked to provide a flexible and reusable system.  I have found a lot of generic documentation that tells you at a high level the best practices as far as how to do this but little showing how you actually implement them.  I need to show him documentation as far as the advantages to using business objects versus data sets and things to that level of detail.  Any help would be appreciated.</p>

Microsoft's
Patterns & Practices group
has published various whitepapers and documents in the form of "architectural guidance" that can be helpful. They recently published a number of
"pocket guides"
as well. Even if you don't follow them to the letter, they're likely to be a great starting point for discussing your particular needs.
That they come from Microsoft may also help add credibility in the discussion with your boss. There's one on
Web Application Architecture
, in particular, that sounds like it may be relevant.