Even i am searching for the same answer,and i doubt winrunner can test .net applications. i found that Test complete form Automated QA comes with full support for .Net.i am still searching for any other options. if you come across any solution, please tell me also.
Have you tried using WinRunner to test your web app? If it's a web app, you'll need to the WebTest Addin for WinRunner.
As far as I'm aware, ASP.NET generates standard (or at least a Microsoft version of) HTML; otherwise everyone would need the .NET framework installed to view the website. So WinRunner with the WebTest AddIn should be able to test your web-app.
However WinRunner 7.01 is quite old, you ever though of upgrading?
The .NET forum is probably the best place to search for answers to "Which tool is best for .NET" questions. It has been raised and answered many times.
Quick Test Pro from Mercury Interactive (makers of Winrunner) is the tool for .NET according to Mercury. Personally, I don't like it, but that's just because I don't like any tool that goes for record/play and instant gratification over coding.