noob question here, what does AA or MSAA has to do with maximum addressable memory address thingy? Does that mean to fully feel the DX10 eyecandies, do we need to migrate to 64bit OS?

there's never an absolute answer.

^^
every generation of gc has their associated generation of games. Compare games released in 2004 and now, both using dx9c, but which one look better overall? 3 years ago people can brag about their rm2k 6800 ultra and its the best card to run all available games released that time. Today we can also brag for rm2k 8800 gtx and it too can play all available games today. The graphic complexity is growing in according to the complexity of GC, back to 3 years ago, no one average joe could realize the importance of MSAA or HDR as it is now.

that's kinda ridiculous requirements to me.
How in the heck 7900GT could be at the same par as 8600GT?
its more like 8600GT is the minimum requirement.
And the recommended proc. saying Intel C2D, they receive bribe from Intel? Totally neglecting AMD counterpart leh

dx10 performance I dunno
but I owned 8600gt before, I can honestly tell you they are nowhere near to 7900gs/radeon1950 in dx9 games