Dont waste money on a Hardware (Workstation ) Card.

Todays Game cards are not that much different for running Maya, the only real time you see a difference is at render, but its seconds and minutes or hours.

Stick with a good "Games" card and a nice chuck of RAM and Maya will whistle dixie forever.

On the x86 v x64 question. I have ran both on my PC, with a x64 OS and theres not much diference, it loads faster, but beyond that theres no real difference that you will notice. I was on Vista x64 for a while, but was fedup with Vista taking 1/2 my RAM just cause it wanted to (I run with 4Gb). I prefer x86 OS and x86 Maya, thats personal, as XP still runs faster on my x64 than Vista x64 does, but thats just Vista...

Its all swings and roundabouts tbh, just make sure u have a good porcessor and a good chuck of RAM and Maya will work away nicely.