All 32 bit systems can use 2 gigs max.  If you know how and your motherboard can support 3 or 4 gigs, then you can use a 3 gig switch.  A tricky and risky solution for those not in the know.  I would suggest a 64 bit systtem if you are going to run 3D.  A 64 bit system takes 4 gigs so you should have little trouble working with 3D.

You can stil run 32 bit programs on a Vista 64 bit system.

As explained, if you can stand to turn off all of the Bells and Whistles then 32 bit Vista will work almost like XP, almost but not quite.  And, as it stands with Vue it really works better in the XP environment 32 bits or 64 bits.  They have not really addressed a Vue packaged for Vista as yet, maybe next year.  

So the choice is really up to the user.

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