I haven't seen XP Unlimited before; it looks promising. (I may give it a bench test when I get a chance...)
As for the unofficial Vista "patch" (a crack, really); when I searched for that the first link was on Pirate Bay. Not a promising start. I'd be very careful with that, and my "official" recommendation would be to use it on non-production "bench-test" type machines only, for "educational" purposes.
(Not that the M$ police are likely to come after you unless you are with a large corporation with multi-million, or -billion, dollar budget for IT; but is it really worth the risk?)