Ask Slashdot: Is SMP worth it?

Here's another question from the ubiquitous Clan Anonymous Coward! I usually don't do AC posts, but the question was rather interesting enough: "Dual socket 7 motherboards are pretty cheap now, and P200 and P233 processors are way under $100. So would buying a dual p233 system be better than a single PII 450? I would be dual booting Linux and NT." What issues do you have to worry about when dealing with SMP (motherboards, memory, heat)? What SMP issues are there with PIIs as well?