if you order Mac OS X right from Apple, they won't know that you are ordering from a Windows-based PC, it's the Internet for heaven sake!
Actually, it is possible for a webpage to find out what browser you are using - and rediculously easily too.
I mean, if x86 PCs can run UNIX, they should be able to run Mac OS X Tiger rather easily,
Technically, yes. Mac OS X runs on standard home PCs perfectly. I'm not sure of the details, but I assume Intel Mac motherboards have some sort of security chip on them that the OS checks to make sure exists. This of course can be bypassed, however as big10p says, it isn't legal to do so.