virtualbox.org

In VirtualPC you can install some app that allows you to drag seamlessly from your VM OS onto your host desktop... making the VM window a act exactly like any window in windows...

Is there a way to get that functionality in VirtualBox?

No, this is not (yet) supported.

Drag'n'drop of files is not supported, but seamless mouse is, after installing the Guest Additions. You should have read the manual first though, as it's all in there .