in reply to web-based application or desktop application?
Another advantage of web apps is that they are automatically platform independent - so long as the page designers permit it to be by keeping it simple. Avoid jazzy dhtml, flash, clientside scripting, etc., etc.
You can certainly save time on your app by getting designers in. It's good that you don't need to let them go nuts for an internal app. Think templates.
Don't stint security just because this is your intranet. HTTPS remains a good idea.