i agree with the points above ...
i just want to add some pro on web app :
1. it looks nice. you can change the themes as well (just change the css) may be desktop app will looks boring to some user but wep app, you can change the themes/design and it will impress you user (and boss)
it is cheaper to implements. For example, if you develop application with .NET you need to have clients that install windows. but in web application, once you develop, any client can access your web apps with any platform.
web app development are simple (once you know about css javascript and framework) it can make your life easier.
No virus and easy to deploy/install for client.
Cons:
UI in web app are more complex and need ability in javascript and css stuff to make a good quality of UI.
I recommend you not to create from scratch (that would be pain) but build the new modules in web apps. that would be wise :)
