Use full screen and don't go to the top of the screen? To completely hide the menubar items you'd have to hack that from OS X side. Or just use Fusion full screen and not see it.
Using full screen and not going to the top of the screen is not a solution, since you always need to go to the top of the screen in Windows because that is where the window bar is when the window is maximized. I also find this problem very annoying and haven't found any solution. I've tried editing the info.plist file and adding the LSUIPresentationMode key with a value of 3 which should completely hide the menu bar even if the mouse goes over it as refered at http://developer.apple.com/documentation/MacOSX/Conceptual/BPRuntimeConfig/Articles/PListKeys.html#//apple_ref/doc/uid/20001431-113616 but it still doesn't work. Any ideas on how to do this? Thanks.