The Intel Core Duo 6700 is a brilliant processor, so I would definitely recomment it.
A:M is a single process program so it doesn't make use of the two cores, but you have all that extra processing power available for rendering in the background, running Photoshop as well, etc.
Get the X1900XTX if you want but it is more then A:M needs. Any modern midrange nVidia or ATI Radeon graphics card is fine. What you have to remember about these monsters like the dual X1900XTX is that they consume lots of power and require a lot of cooling. A $200 - $300 nVidia or ATI graphics card is still easly fast enough for A:M and will probably run cooler and quieter. A quiet PC is definitely appreciated when someone has to sit next to it for many hours a day.
A:M only uses the graphics card acceleration to speed up the realtime wireframe and shaded rendering to the screen in the editing process. No feature of the graphics card is used in the final renders. As a result, you will get the same performance and quality in the rendering of the final movies with a dual SLI X1900 or a cheap $50 graphics card.
A higher priority is to spend money on Ram (1 to 2GBytes of fast high quality RAM) and a really good screen (like a high resolution 21" LCD).
Insist on Windows XP Pro operating system. Don't touch XP Home because it has crippled networking and if your son gets really interested in Animation, he will eventually need networking.
Getting a dual X1900XTX sounds like you are building a super game PC and you might find it hard to keep a gaming PC "clean" enough to run A:M reliably.
Richard Harrowell.
Thank you ssappington and Richard for your responses.
Richard, please help me understand your comment on keeping a gaming pc clean enough to run A:M reliably. Based on your comments we would build a pc with fast processor, 2 gig+ fast memory, and 20-21 1600x1200 monitor and WinXP professional. Do we not want to play games on this machine if A:M is first priority?
Dennis (am_dad)