It seems the 64-bit OS demand for Watch Dogs is not exactly accurate, so sayeth Graphics Technical Director Sebastien Viard at Ubisoft. It seems the 'leaked' PC specs yanked from Uplay are "not official".
This news applies to the Assassin's Creed IV: Black Flag PC specs too. 32-bit Windows will be fine, with less demands made on hardware at the 'lower spec' level.
"These are not official configs. The real specs out soon and will be lower", Ubisoft's Sebastien Viard. Watch Dogs releases on PC, Xbox 360 and PS3 November 19th in the US, 22nd in EU.
Pay no heed to thesebunch of lies. We got trolled by Dedsec.
Thanks to wolfsrain for the tip off.