By Core series, I meant the entire Core Duo, Core 2 Duo and Core 2 Quad ranges.

My experience so far, is that the situation vis a vis 64-bit drivers is far better with Vista than with XP x64. Generally everyone is writing both 32 & 64 bit drivers at the same time. AV is still a big problem though - even MS haven't made a 64-bit OneCare Live version yet