According to Wikipedia, Windows provides one of the best ASLR on the market. I'm not sure why you are singling out Windows as a weak point here.
Windows has for a long time been the prime target of most exploits, and thus have spent considerable effort, on OS-level, to prevent the potential damage. OS X for instance, has almost none of the OS-level security features found in Windows and is a much easier target to exploit.
http://en.wikipedia.org/wiki/Address_space_layout_randomizat...