I would only consider running XP (reluctantly) on hardware which originally had XP installed on it.
XP seems to have this aura of "this is wonderful" when, in fact, it was really the first of the "almost proper" operating systems which actually worked (sort of)!
While ME and Vista were two major disasters Win 7 actually works and I would never go back (and with a core i7 Sandybridge processor it would be madness anyway)
Many corporate users still have XP on their estates (my employers do as it is mandated by our customers!!!) but are rapidly re-evaluating their options as the support expires.
Just because the local NHS uses XP isnt a recomendation in my eyes - look at the huge NHS IT project that has failed, presumably the continued use of XP is because of this and some rubbish software that hasnt been updated for years which requires XP (normally because of dependancy on Internet Explorer 7 or earlier which isnt supported on Win 7).
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