Adobe Photoshop 4.0 with Vista 64 bit?

Ok so I first bought photoshop 4.0 then i have an upgrade to cs2 disc but when i put 4.0 in is says 16 bit is not compatable with vista 60 bit and to contact vendor. so if i ask photoshop will they giv me it for vista or make me buy it again? also if i could make my vista with a lower bit [i think 30bit was an option] would i be able to run it?