Which model AAO is it? The 110, the 250?
I have an Acer Aspire One D250 with Intel GMA950 and 1GB RAM, running Windows XP (factory default), and Sacrifice runs like a dream. I even edited the registry to make it run widescreen, and at the default netbook resolution (1024 x 600) it suffers from none of the problems noted at the WSGF (i.e. no disappearing objects, as far as I can tell).
Vista is notoriously problematic and quite a resource hog in and of itself, so I am quite surprised it even runs on a netbook. To the best of my knowledge, Acer doesn't release any netbooks running Vista for exactly that reason, and if you're running an illegal version of Vista (not saying that you do, of course), that might be a problem too. My first solution would be to switch back to Windows XP or, if you are unwilling or unable to go back, I would upgrade to Windows 7 and see if that works. While the latter is a slimmed-down version of Vista, it is somewhat better.
Edit: changed a word.
Post edited June 02, 2010 by JoshoB