This is not a trivial topic, but it’s necessary at times to have classic ASP pages controlled by security in ASP.NET. Scott gives some tips on how to accomplish this.
Scott also refer’s us to Stefan Schackow’s excellent book: ASP.NET 2.0 Security, Membership, and Role Management. This is really a GREAT book. I’ve read every word of it. In fact, I was a technical editor for the book, so I can attest to its excellent technical content and depth.