real story VISTA RTM ?

Can anybody, who knows, tell me what the real situation is with the RTM of
Vista. I downloaded a copy via Internet. If you install it without a number
it gives you 30 days to activate. If you use that fake number it gives you 3
days to activate.If you try the crack it will obviously take you back to RC2
or so with its limitations.Can one use the RTM and buy a number from MS when
it becomes available ? Are the RTM's on MSDN the same than the ones from the
Internet ? regards