>So here's my question...for a rich UI in a 'web-based' environment, what would be the benefits (and pitfalls) of using WinForms over ASP.NET??
>
>Thanks,
>Kevin

Who is your audience? If you are targeting consumers you would want to stick with a browser front end. If your audience is intranet or a small number of business partners, then you may be able to get by with Winforms and/or Web Services.

Architect your system using n-tier design. Then you can mix and match front ends.