So Macs are too powerful for people? I thought you said they weren't very good. Okay, you can spend $3,000 on either system. The Dell will be slower, older technology that won't last you several years until you think of getting a new one, while the Mac will last you much longer.
For a PowerMac, they're cheaper to buy, cheaper to own, faster, more usable and more stable. You can't touch that with a Wintel box.