2 processor systems have been around for a long time..

They use special motherboards which are built specificaly for this task. They have a fan ontop of each processor and get no more hotter than a normal system.. The only draw back is that they are expensive to build (especialy my system.. it uses ECC registered Ram only.. £90 for 512 meg and you need to buy them in pairs !! ) Multi processor systems are usually found in servers..

No they dont run twice as fast, but when it comes to number crunching (like rendering) they dramatically reduce the time taken to render a scene. Well worth the money if you are serious about modelling, but not worth teh money of you are just doing it part time and spend more time playing games.. I found a slight FPS increase in my games, but nothing worth the money I paid to build the system.

Cavalt... I personaly would go with the AMD 64 bit chip. If the next release of Maya runs under the Win XP 64 bit software, then you will be able to take advantage of it. There is no shame in AMD, they have been very impressive for a few years now, especialy the 64bit chips