n-Layered Design Confusion

Can anyone provide me with a web link that shows a correct approach of n-Layered design with example source-code in VS2005 and C#?

I am confused in one point, If I am creating layers like the following:

   UI
   |
Business Logic
   |
  Data Access

then how can I achieve true OOP?

Coz In OOP all activities should be encapsulated within an Object.

According to my thought, this should be layered like this:

   UI
   |
Business Objects
   |
Business Logics
   |
Data Access

But when trying to design layers like this I experienced Circular Reference Problem.

One of my buddy told me that, he solved this problem with Reflection.

So what is the industry-standard approach in separating a c# application into layers?

And a burning question is, which layer hosts the OR-Mapping?

ansaurus