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		 Without permissions you'd be fine with a FAT32 file system. 
 
However, permissions in WinXP and OSX are two entirely different systems.   
 
I'm pretty sure that the only way be your second option, setting up a server and setting the permissions there.  I have no idea where'd you go from there though, maybe a linux install with Samba? 
		
		
		
		
		
		
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