I'll be the devil's advocate on this one.
I had been planning on replacing my old Core Duo MacBook Pro with a new MacBook Air. I had already passed my MBP on to my wife, and had been using her Core Duo MacBook as my primary portable while I worked on selling my PC desktop to buy the Air.
A co-worker had expressed interest in buying my desktop, but needed to save up more money first. He then won an iPad. I made the mistake of mentioning these two facts to my wife in near-proximity, and her response was "Oh, really?" Needless to say, I promptly sold him the computer and got the iPad as partial payment. (Still shrink-wrapped.) If my wife wants an iPad, so be it, I can always save up a little more, sell something else, to buy the MacBook Air.
Well, in the two weeks since then, my wife's interest in the iPad has waned, and I have found that, especially when used with my Apple Bluetooth keyboard, I nearly never need the full-blown MacBook. So I bought myself the ZaggMate keyboard case, and have forgotten about the MacBook Air. Smaller, lighter, does 99% of what I need to do on the go. I'll take the money I had been saving for the Air and get a new desktop sooner. (I'm waiting for the update to the Mac mini, then, hopefully they'll have a quad-core model as an option, and I'll get the mini server to be my desktop.)