Vista - Power Options problems Vista Ultimate

If I leave Virtual PC with Vista Ultimate on Full Screen and leave the
computer the screen saver for Vista will not start at the specified time nor
will the monitor turn off at the specified time. If I remember to use right
alt/enter before leaving the computer then power options on the host
(running XP ProSP2) take over and the screen saver runs on the host machine
and then the monitor shuts down as I have specified. Usually with VMWare
Workstation machines (XP) the power options for those machines work even if
the computer is left with the virtual machine on Full Screen.

I have also noticed that if, instead of just leaving the computer with the
screen showing the virtual machine in the right alt/enter position, I
actually minimize the virtual machine to the host's task bar then the
virtual machine runs the screen saver at the designated time and, of course,
the host runs the main screensaver/monitor shut down at the specified times.

So, why doesn't the virtual machine's screensaver, and then shut down of the
monitor, work properly when the virtual machine is on Full Screen?

This is slightly off topic, but can anyone tell me why, in Vista, the screen
saver settings are not with Power Options (as they have always been with
past OSes) and instead appear to be reachable only from the Help file? That
is really weird. Plus, to tell users that a screen saver is not needed
these days (which is what the Vista help file says) is untrue and
irresponsible. Some folks still use CRT's and even LCDs can experience burn
in and the back light can die. A screensaver should always be used to save
the life of the monitor (assuming you bought a nice, expensive monitor). Of
course, the monitor should always be set to turn completely off after a few
minutes (assuming one never shuts down the hard drive) even if it is an LCD
with little power consumption.