<p>When I press F5 in Visual Studio 2008, I want Google Chrome launched as the browser that my ASP.NET app runs in. May I know how this can be done?</p>

Right click on an .aspx file and click "Browse with..." then select Chrome and click "Set as Default." You can select more than one browser in the list if you want.
There's also this really great
WoVS Default Browser Switcher Visual Studio extension
.