One of the problems is that people always only look at the hardware specs. You specifically discounted OS X, which is a major reason to go with a Mac, especially with the GPU-accelerated libraries that free your CPU for other tasks (effectively giving you a faster CPU). You also discounted the tons of useful software that comes with a Mac.
Also, did you consider size as a factor in this deal?
If you're happy with your Dell, that's great. But you did pay for Windows in that Dell and got very little software-wise.
And you don't pay for Apple's OS when you buy a Mac? Why should Windows be free?
Software was one of the major factors in buying the Dell. I already have MS Office and a few other Windows software packages that I would have had to repurchase by going with the Mac.