I assume he's referring to hyper threading when he mentioned dual core.
Like everyone else previously posted if you want to run a newer version of ubuntu your only option would be with a different desktop environment that doesn't require the additional juice.
Also just because Microsoft is going to stop supporting XP in April 2014 doesn't mean it will stop working. Your just going to stop receiving updates for it. Once April rolls around I would try to keep internet use on the XP side of things to a minimum.
Good luck!
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