Thank you for your reply. I read bernard's answer but it did not sound like an assertion to me...
"I'm not sure but per Calos's blog this is supported on Vista and W2k8 only"
As he said, he was not sure and Carlos' blog article was written nearly 2 years ago...giving some hope on a wider support (especially with the IIS Manager now running on XP)
A pity that it's not mentioned anywhere else but in a blog...I would have expected this to be stated in the MWA article on IIS.Net, or at least in the MSDN or Technet docs.
Anyway, thanks for answering and hopes this will more clearly said for others!