I've got a Windows 7 machine set up on Paralells.  

Everything is working fine. Can access internet from IE or other browsers on my Parallels.

However, when trying to debug a web application in Visual Studio 2010 (by pressing F5 for example) then my default browser in OSX launches, which is great, with localhost:4243 (or whatever port Cassini has allocated on my vm)

Naturally, this doesn't find anything...

What do I need to do to either my parallels vm, or the settings on OSX to get debugging working? ie- my mac talking to the vm?