Building an Upgradable Dual Processor System

AntMan asks: "OK. I am building a new system for myself. Now checking on pricewatch.com I noticed that Dual processor motherboards can be had for under $100. My budget was $800 tops. But on doing some research I realized that I could build a 866 Mhz dual Celeron system in that much with change left over. But when I looked on Anandtech, Aceshardware, and tomshardware, I found very few reviews/guides for building dual processor systems. Additionally I wanted to build a system, in which I can put in a couple of cheap 433MHz celerons PPGAs, and hopefully upgrade to a couple of 1GHz PIIIs when the price is right (in about a year or so). So my question is ... Is this possible? And what MB would people recommend?"