I have windows 7 64 bit, and it is now ignoring the hosts file!!
This seems to have happened, just after running some tools suggested to me at bleepingcomputer.com. The tools were OTL.exe and OTM.exe. (This was part of an effort to remove a not incredibly bad malware, that would redirect perhaps 1 our of 20 google links I clicked to another site)
Anyway -- windows is ignoring the hosts file now, and the people at bleepingcomputer claim that all the tools did was clean out the host file -- they did nothing to stop windows from paying attention to it.
I can put something in the hosts file, and then try running a ping, and it will not find it.