Have you ever used Virtual PC on a machine that just didn't want to allow the window to resize as expected? I have. As a matter of fact, I've got three laptops I'm on regularly as well as two desktops and one of them just has to be the bastard of the group. I maximize the window and the area taken up by the VM isn't the entire screen. It's kind of an odd thing to describe. I wish I could take a screenshot of it, but when the window is maximized, the host OS can't be accessed. Well, not that I know of, anyway. So, if my guest OS is set to 640x480, the host resolution stays at the original value, 1680x1050 in my case (on a widescreen monitor), and the rest of the screen outside of the 640x480 is black. I tried playing with the guest screen resolution, but could never get it to work as it has so many times on other machines. As a matter of fact, it only allowed me to select standard resolutions and not even widescreen resolutions, which only added to my aggravation. Luckily, someone clued me in on a little secret: Virtual PC only supports a host OS resolution of 1400x whatever. In my case, that's 1440x900. But... why didn't resizing my host OS work!? Bah... stupid VPC... You have to completely shut down VPC and restart it for it to recognize and accept the change. From there on, you should be golden.
Umm... You gotta be kidding me, right? Why isn't this mentioned anywhere? VPC should tell me of this problem and try to remedy it on its own. How? Easy. Why not display a warning sign on the VPC Console? Give me a button or setting I can use to automatically set my resolution to 1400x when I maximize a VM, but go ahead and switch it back when I'm not maximized. Sure, there'd be a slight delay in maximizing the window, but if I know what's going on, I'm fine with that.